This should not happen and is, indeed, a bug. As I mentioned above, I have logged a bug report with the developers and it should hopefully be fixed in the next version.

This is what should happen (and what does happen when using my code above).

This is not what happens. The Gallery Title is displayed when the thumbnails are visible (and hidden when the thumbnails are hidden).
The Juicebox-Pro API event onShowThumbs is fired each and every time the thumbnails are toggled (on or off) so the code within the onShowThumbs function is run each time the user clicks the Thumbs Button on the Button Bar.
When the thumbnails are showing, the Gallery Title is shown (using CSS via the jQuery function show()) and when the thumbnails are not showing, the Gallery Title is hidden (using CSS via the jQuery function hide()).
Juicebox comes with its own version of jQuery (bundled within the 'juicebox.js' file) so once this has been loaded on a web page, basic jQuery functionality is available. However, if your web page requires jQuery, then I would strongly recommend that you include your own version of the jQuery library (rather than relying on the built-in version that comes with Juicebox). I could have written the function using standard JavaScript as follows (which has exactly the same functionality but is a lot less compact than the one-liner above)

jb.onShowThumbs = function(showing) {
    var elements = document.getElementsByClassName('jb-area-large-mode-title');
    var element = elements[0];
    if (showing) {
        element.style.display = 'block';
    }
    if (!showing) {
        element.style.display = 'none';
    }
};

If you want to incorporate my solution into your own gallery, just give your 'juicebox' object a variable name (change new juicebox({ to var jb = new juicebox({) and add the onShowThumbs function below your own gallery's embedding code (still within the <script></script> tags).

I hope this helps.

Try removing all CSS applied to the 'juicebox-container' div and apply it to the gallery's parent container instead.
You currently have inline CSS applied directly to the 'juicebox-container' div and JavaScript applying CSS rules (max-width, margin-left and margin-right) to the 'juicebox-container' div on retina screens.
Leave your gallery's width at 100%, leave the gallery's container as <div id="juicebox-container"></div> and apply any CSS (either directly or via JavaScript) to the gallery's parent container (your div with id="wrapper") rather than to the 'juicebox-container' div itself.
Hopefully this will help.

Unfortunately, it looks like your gallery may be affected by a known bug in the current version of WP-Juicebox (affecting NextGEN and Picasa Web Album galleries) which will be fixed in the next version.
Please download this zip file [File removed.], extract the 'wp-juicebox.zip' from within and use it to replace the 'wp-juicebox.php' file on your web server (in your 'wp-content/plugins/wp-juicebox/' directory), overwriting the existing version.
Hopefully this will solve your problem.

Once you have your new download link, you will be able to download the current version of Juicebox-Pro (v1.4.2) and use the Pro files to upgrade WP-Juicebox by following the instructions here.

The two most likely causes of a completely blank screen where the gallery should be on a mobile device (where the gallery displays OK in desktop browsers) are either:
(1) Viewing the web page over a 3G connection rather than wi-fi.
... or:
(2) JavaScript being disabled in the browser.

If a 3G connection is being used, please see this FAQ:
Why can't I view my gallery on a 3G mobile connection?
If you have already implemented this solution (and it sounds like you may have done), please double-check your .htaccess file as the solution should work fine.

This would not be as easy to achieve as my Back Button example above. It would technically be possible to track down all the CSS classes of the elements that you initially want to hide and use CSS and JavaScript to hide them but Juicebox would know nothing of this manual modification and would still think that the overlay is visible and when the user first clicks on the Info Button, Juicebox would hide the already hidden overlay (and it would look like the Info Button does not work).
The same thing happens when firing toggleOverlay() within onInitComplete() (from the Juicebox-Pro API).

It sounds like you may have purchased Juicebox-Pro recently but if not, please ensure that you are using the current version (v1.4.2) to ensure that any bugs which were present in previous versions but which have since been fixed are not contributing to your problems.
If necessary, instructions for upgrading can be found here.

(1) Try viewing your gallery in different browsers (Chrome, Firefox, Internet Explorer, Opera and Safari) to see if your problem is visible in all browsers. Also, please post the URL to your gallery so that I can take a look for myself.

(2) If you want to tweak the position and/or style of your gallery's image titles and captions, then you can use HTML formatting as documented in this FAQ (using inline CSS properties such as margin and padding as necessary).

(3) The speed at which images load will be dependent on a number of factors:

• The speed of your web server.

• The speed of your internet connection.

• The file size of the images in your gallery.

• The value of the imagePreloading configuration option.

You have little or no control over the first two factors but make sure that your images are not too large (creating a gallery with JuiceboxBuilder-Pro's default settings should produce images of approximately 120KB each which should be suitable for web gallery use in most cases) and try changing imagePreloading (in JuiceboxBuilder-Pro's 'Customize -> Main Image' section) from its default value of PAGE to NEXT so that only the first couple of images in the gallery (rather than all the images on the first thumbnail page) are preloaded when the gallery is initially displayed. This might help speed up the initial display of the gallery.

(4) Pinch-zoom is not actually disabled but the start of a pinch-zoom gesture is likely to be interpreted as the start of a gallery-specific gesture (such as a swipe to navigate between images). If you are very precise, you might be able to pinch-zoom within a gallery. However, there is nothing that can be done to override the current behavior.

(5) This will be partially dependent on the device/hardware being used to display the gallery and the browser, too.
All you can do to maximize the smoothness is to minimize the load on the browser by ensuring that your images are not too large (again, a file size of between 100KB and 120KB should be about right for most scenarios). Preloading images (setting imagePreloading to either PAGE or ALL) may also help (but might slow down the initial gallery display).

(6) Thank you for providing your gallery's configuration options. I have been able to replicate the problem in a test gallery of my own and have logged a bug report with the developers. It looks like the problem is caused by setting showSmallThumbsButton="FALSE". Hopefully the bug will be fixed in the next version of Juicebox-Pro but, in the meantime, the only workaround would be to set showSmallThumbsButton="TRUE". (I realise that you would rather not use this setting but it appears to be the only way around the problem until it is fixed.)

Please make sure that you are following the embedding instructions here.

Perhaps the troubleshooting FAQs will help.

If you would like me to take a look to see if I can figure out why your gallery does not display, please post the URL to your gallery's web page. Thank you.

Perhaps I am misunderstanding your problem. I am not sure what you mean by "nothing altered the hiding of all images in full screen mode".
I have expanded your gallery in Chrome, Firefox, Internet Explorer and Safari on my PC and the expanded gallery looks similar in all browsers.
Could you please upload screenshots somewhere (and provide links) of the gallery's fulscreen display in Safari and in other browsers so that I can see what you are seeing? Thank you.
It might also be worthwhile clearing your browser's cache before reloading your gallery's web page to ensure that your browser is fetching and using the most recent versions of your gallery files.

If you would like to make any suggestions for future versions of Juicebox-Pro, then please post them in the Feature Requests thread. This keeps them all together and ensures that they are not overlooked. Thank you.

As you are already using PHP, you could use a PHP include as follows.

(1) Change the filename of 'elaimet.xml' to 'elaimet.php' and change its contents to the following:

<?php header('Content-Type: application/xml'); ?>

<juiceboxgallery 

    useFlickr="true"
    flickrShowTitle="false"
    flickrShowDescription="true"
    flickrImageSize="ORIGINAL"
    flickrImageCount="200"
    flickrUserId=""
    flickrSetId="721576XXXXXXXX"
    flickrSort="date-taken-desc"

<?php include 'extra.php'; ?>

/>

(2) Put your common configuration options into a file named 'extra.php' (just as below):

backgroundColor="rgba(248,248,248,1)"
buttonBarBackColor="rgba(0,0,0,.4)"
buttonBarIconHoverColor="rgba(255,0,0,1)"
buttonBarPosition="TOP"
captionBackColor="rgba(248,248,248,.8)"
captionHAlign="LEFT"
captionPosition="BELOW_IMAGE"
displayTime="4"
enableAutoPlay="true"
enableDirectLinks="true"
frameWidth="1"
galleryFontFace="Arial,Helvetica,sans-serif;"
galleryHeight="450"
galleryTitle=""
galleryTitlePosition="NONE"
galleryWidth="500"
imageFrameColor="rgba(0,0,0,.4)"
imageNavPadding="30"
imageNavPosition="IMAGE"
imageShadowBlur="0"
imageShadowColor="rgba(0,0,0,0)"
imageTransitionTime="0.2"
imageTransitionType="CROSS_FADE"
importCaption="IPTC"
importTitle="IPTC"
languageList="Näytä pistenavigointi|Piilota pistenavigointi|Suurenna kokoruutuutilaan|Sulje kokoruututila|Avaa kuva uudessa ikkunassa|Kuvat|Seuraava kuva|Edellinen kuva|Soita musiikki|Pysäytä musiikki|Näytä tiedot|Piilota tiedot|Aloita näytös|Pysäytä näytös|Näytös päällä|Näytös suljettu|Mene takaisin|Osta tämä kuva|Jaa: Facebook|Jaa: Twitter|Jaa: Google+|Jaa: Pinterest|Jaa: Tumblr|/"
maxCaptionHeight="30"
navButtonBackColor="rgba(0,0,0,0.4)"
navButtonIconHoverColor="rgba(255,0,0,1)"
showAutoPlayButton="true"
showImageNav="false"
showImageOverlay="ALWAYS"
showNavButtons="true"
showOpenButton="false"
showPagingText="False"
showSmallThumbsOnLoad="true"
showThumbsButton="false"
showThumbsOnLoad="true"
splashButtonText="Avaa galleria"
textColor="rgba(0,0,0,1)"
textShadowColor="rgba(0,0,0,0)"
thumbFrameColor="rgba(255,0,0,0.8)"
thumbHeight="60"
thumbHoverFrameWidth="1"
thumbSelectedFrameWidth="2"
thumbShadowColor="rgba(0,0,0,0)"
thumbsVAlign="BOTTOM"
thumbWidth="60"
topAreaHeight="0"
topBackColor="rgba(255,255,255,0)"
useFullscreenExpand="true"

(3) Use the following embedding code (changing the file extension of the configUrl):

<!--START JUICEBOX EMBED-->
<script src="galleriat/jbcore/juicebox.js" type="text/javascript"></script>
<script>
    new juicebox({
        configUrl: "galleriat/elaimet.php",
        containerId: "juicebox-container",
        galleryWidth: "500",
        galleryHeight: "450",
        backgroundColor: "rgba(248,248,248,1)"
    });
</script>
<div id="juicebox-container"></div>
<!--END JUICEBOX EMBED-->

Thank you for reporting this problem. I have been able to replicate it in a test installation of my own.

It looks like it happens when creating a new Juicebox gallery within svManager as well as when importing a gallery.
Just click on the 'Pro' tab of any Juicebox gallery and the 'SV' logo and 'SimpleViewer Pro Settings' label will be displayed.

However, the problem seems to be just cosmetic within the svManager interface. The actual configuration options available are those for Juicebox-Pro so, although it may look confusing, the actual functionality is fine.

I have notified the developers of this problem and hopefully it will be fixed in the next version of svManager.

In JuiceboxBuilder-Pro's 'Customize -> Color' section, set the 'Opacity' of the 'Text Shadow Color' to '0' (zero).
If editing your gallery's XML file directly, set textShadowColor="rgba(0,0,0,0)". The last rgba parameter is the opacity (the 'alpha' channel).

Have you checked the .htaccess file(s) on your web server yet?
It looks like there may be rewrite rules in your .htaccess file(s) which might be causing teh problem you describe.

Just for testing purposes, take a backup of your .htaccess files(s) and then temporarily  remove them from your web server to see if this makes a difference.

I would also check with your web host to see if they have made any changes recently which might be contributing you your problem.

Opening an HTML web page that definitely exists on your server and getting an error 404 (file not found) message certainly sounds like it is directly related to your web server or .htaccess file(s) rather than with Juicebox itself.