Maybe you're just seeing the Splash Page (see here for details and scroll down).
The Splash Page is an image placeholder for the gallery which, when clicked, will expand the gallery to fill the browser viewport (to give the gallery as much room as possible).
By default, the Splash Page will be displayed on mobile devices when a gallery is embedded in a web page alongside other content (where the gallery might be too small to use). By default, Juicebox uses the first image in the gallery as the Splash Page image (and crops if necessary). You can change this if you like via the splashImageUrl option (in JuiceboxBuilder-Pro's 'Customize -> Splash Page' section).
You could also choose to not use the Splash Page at all by setting showSplashPage="NEVER".
Please note that these are Pro options (not available in Juicebox-Lite).

Also, if you are using a fixed value for your galleryWidth, try using a percentage instead (e.g. 100%).
However, please be sure to set widths for all parent containers using CSS so that your browser knows what the gallery's width should be 100% of.

Unfortunately, WordPress changed some of their internal code which now prevents the 'Add Juicebox Gallery' button from appearing in the Gutenberg editor.
With an update to WP-Juicebox unlikely, the best solution would be to create the gallery on the 'WP-Juicebox -> Manage Galleries' page and then copy the shortcode (provided on the 'Manage Galleries' page after creating a new gallery) into your page or post.
This should still work fine.

I should be able to see your gallery's 'config.xml' file here: http://www.edpeet.com/gallery/config.xml
However, going directly to that location in a browser results in the message "Your request was blocked by the Web Application Firewall".
You should be able to view the 'config.xml' file like in this demo gallery: https://juicebox.net/demos/lite/full/config.xml

It looks like something on your web server is blocking access to your gallery XML files and this is causing your problem.
This makes sense as, if you have changed nothing on your website but the galleries now no longer function, then this suggests that something must have changed on your web server to cause the problem (as none of the gallery code itself will have changed).

Please check in with your web host and ask them to allow XML files (at least your gallery XML files) through your Web Application Firewall.
This should resolve your problem.

If you have trouble with an old forum account, please email me at steven@juicebox.net (with a note of your forum username) and I can sort you out with a temporary password so that you can log in (and then change the password without needing an email confirmation).
Incidentally, any problems with your forum account would have no effect on your website. This is a completely separate issue.

I cannot be sure, as I don't have access to all the files involved, but it appears that you might have some custom CSS in your 'styles.css' file that is overriding the default Juicebox CSS and interfering with the layout of the gallery's Button Bar.

Check your 'styles.css' file for any generalized CSS rules that the gallery might inherit. Look out for any CSS rules that, for example, apply to all 'img', 'p' or 'div' tags (rather than just specific instances of these tags through use of ids and classes).

I hope this points you in the right direction.
However, if you continue to experience difficulties, please post the URL to your gallery's web page so that I can see the problem for myself.
Once I'm able to see the gallery live on your web server, I'll be able to inspect all the files and hopefully determine the cause of the problem.
Thank you.

You can manually change the name of your gallery's configuration file via the configURL Embed Option.
Just add a line such as the following to your gallery's embedding code and rename your gallery's configuration file accordingly.

configURL: "juicebox-data.xml",

For example:

<script src="jbcore/juicebox.js"></script>
<script>
    new juicebox({
        containerId: "juicebox-container",
        configURL: "juicebox-data.xml",
        galleryWidth: "100%",
        galleryHeight: "100%",
        backgroundColor: "rgba(34,34,34,1)"
    });
</script>
<div id="juicebox-container">

Apologies for my previous reply (which I have since deleted as it was simply incorrect).
I completely forgot about the Embed Options for a moment as they are not actually available within the JuiceboxBuilder-Pro interface but they are available for manual use.

svBuilder-Pro is the AIR application for building SimpleViewer-Pro galleries.
SimpleViewer-Pro (and svBuilder-Pro) relied on Adobe Flash Player and, due to the demise of Flash, they were retired back in 2017.
We then released Juicebox-Pro (and JuiceboxBuilder-Pro) as a HTML alternative (with no reliance on Adobe Flash Player).

It sounds like the layout you are referring to may be from Showkase (perhaps from one of the demo sites here).

With Juicebox-Pro, you can create as many individual galleries as you like. However, if you would like to link them all together, then you would need to do so manually following the instructions and online examples in the Embedding Multiple Galleries support section.
(Also, I've created a single-web-page solution to quickly and easily link together a few galleries which you can find in our online forum here.)

If you are looking for an automated solution to creating and listing multiple galleries, then Showkase might be a more suitable solution for you.

Showkase is a PHP web application (installed on your web server rather than your computer) which allows you to create a complete portfolio web site (integrating multiple galleries) online.
Showkase has full support for Juicebox-Pro and the galleries can be created within the application itself in a web browser interface (or created with JuiceboxBuilder-Pro and imported).

You can create Gallery Index pages and have as many galleries listed on each Gallery Index page as you wish.
Each gallery is represented by a thumbnail image with the gallery title displayed below and the gallery is opened when the user clicks on the image.
Demo sites created with Showkase can be found here and a sample Gallery Index page can be found here.

Showkase can also create non-gallery pages (About, Basic and Contact pages) where you can add information about yourself (or any other content you like).
All of this is done automatically within the Showkase interface without the need for any manual coding at all.
You can take a look around the Showkase interface by logging into the 'Live Demo Admin' here.

Showkase can be purchased as Showkase-Standard (which comes with Juicebox-Lite, the free version) or Showkase-Pro (which comes with Juicebox-Pro).
The only difference between Showkase-Standard and Showkase-Pro is the bundled viewer (Juicebox-Lite vs Juicbeox-Pro).

There is more information on the differences between Juicebox and Showkase in this forum thread.

Have a look at all the links above and if you have any questions, please let me know. Thanks!

Your custom dimensions match well with the Small, Medium and Large image dimensions that Juicebox-Pro uses by default for its Multi-Size images (800 x 600, 1024 x 768 and 2048 x 1536 respectively).
These default dimensions have not changed since Juicebox-Pro was introduced but I think they are still pretty good default values that cover most scenarios.

Of course, one person's site might have a completely different target audience to someone else's site whereby visitors might be more inclined to view the site on a mobile device (or conversely, on a large desktop monitor), in which case, you might want to change these values accordingly.

If you are using Multi-Size images for a Juicebox-Pro gallery within Showkase, there's no quick and easy way to tell which image size is being served up without delving into the browser's developer tools to see if the image originates from the 'images/' folder (Medium), the 'images/small/' folder (Small) or the 'images/large/' folder (Large).

I've just checked and Juicebox v1.5.1.2 galleries still display and function OK in Firefox 146.0 (64-bit) on my WIndows 11 PC.

If you are having trouble viewing galleries locally in Firefox (before you upload them to your web server), then please try changing the setting noted in this FAQ: https://www.juicebox.net/support/faq/#local

If you continue to experience difficulties, please let me know more about the problem you are facing.
Let me know whether the problem happens when viewing your galleries locally or from a web server.
Also let me know exactly what the problem is (what happens or does not happen) and if you see any error messages along the way.
With a little more information, I should hopefully be able to help further. Thank you.

Google Translation:

I don't see a speed increase when trying this on a Windows PC and, knowing how JuiceboxBuilder works, I don't actually understand why there should be a speed increase on any system but I'm genuinely glad it works for you!

I'm not 100% sure of your exact method.

If I do this (manually replace the images in the 'images' folder and click 'Save' on the 'Publish' panel), JuiceboxBuilder immediately reinstates the original images (as I've bypassed the 'Add Images' routine on the 'Images' panel and JuiceboBuilder has no knowledge of the new images in the 'images' folder).

Are you manually adjusting the 'imageURL' entries in the gallery's 'config.xml' file (to reflect the new image filenames)?
How are the thumbnail being generated?

Maybe I'm not following your instructions correctly.

If you don't need JuiceboxBuilder to resize your images, then you could deselect the 'Resize Images' checkbox on the 'Images' panel. This should speed up the 'Add Images' process a little.

Where did you get that information? The source might give me a clue as to what is going on. Thanks!