I have tried this for myself but have been unable to replicate the problem you describe.
I can save a gallery to a Google Drive Sync folder in JuiceboxBuilder-Pro and and then open it with no problem.
Also, if there are any non-gallery files in a gallery folder, JuiceboxBuilder-Pro should just ignore them (and it does in my own tests).

What files do you see that Google Drive adds to your folders (I cannot tell from your video)?

Perhaps you could zip, upload and post a link to the complete gallery folder that crashes your JuiceboxBuilder-Pro so that I could take a look for myself.
I could place it in my own Google Drive Sync folder and try opening it in JuiceboxBuilder-Pro to see what happens.

If you are trying to preview your gallery locally (on your computer), please use either Firefox or Opera.
It is not possible to display a gallery locally in IE11, Chrome or Opera due to a security restriction whereby these browsers cannot load local XML files.

Please note that your gallery will display fine in all browsers when has been uploaded to a web server.

Unfortunately, I have no news to report at the moment and there is no ETA on the fix/next version of Juicebox-Pro.
All I can say is that the developers are aware of the problem and are working towards a solution.

If you are referring to galleries generated by the Lightroom plugin, open the plugin's 'juicebox.lrwebengine/index.html' file (the template file which the plugin uses to generate the gallery's 'index.html' page) in a plain text editor and remove the following line (line 7):

<meta name="description" content="This is a Juicebox Gallery. Get yours at www.juicebox.net" />

All thumbnails in a Juicebox-Pro gallery will have the same dimensions (set via the thumbWidth and thumbHeight configuration options). It is not possible to have thumbnails of different sizes within a gallery.
Essentially, the thumbnails are designed as a navigation device. The main images themselves are not cropped (as long as imageScaleMode is set to SCALE or SCALE_DOWN).

If you like, you could post this as a suggestion for a future version of Juicebox-Pro in the Feature Request thread.
This keeps all the feature requests together and ensures that they are not overlooked.

Try setting expandInNewPage="TRUE" (in JuiceboxBuilder-Pro's 'Customize -> General' section).
For more information on the expandInNewPage configuration option, please see here.

We plan to introduce the ability to set a separate color for the expanded page background (complete with its own transparency value) in the next version of Juicebox-Pro which should provide a solution to this issue.

Unfortunately, I do not have a Windows Phone on which to test.

Are you referring to the Media Library page in the admin section or the frontend pages?
If I know what page(s) fail to scroll, I will be able to know what scripts WP-Juicebox has loaded on the page(s) and I should have a better idea as to what might be causing the conflict.
If you are referring to the frontend pages, then please post the URL to your site so that I can take a look for myself.
Also, what happens if you deactivate MP6 but keep Media Grid activated?

Thank you for fixing the HTML errors on your page. At least we can eliminate them from the problem now.

On further investigation, the problem may not be due to global CSS.
If you load the gallery from the a menu page and the layout appears broken, try resizing the browser window and you should see the gallery redrawn and look OK.
The problem seems to be with how your theme seems to load everything on the page at once and then selectively display whatever is chosen by the user. When the Juicebox code is first run on the page, the container into which the gallery is embedded is not visible on the page at all (and Juicebox may not be able to determine what its dimensions should be until its parent container is displayed).
Try changing the gallery's width from 100% to a fixed pixel value (such as 800px) to see if this makes a difference.

Also, when the gallery's link is clicked, you could try forcing the gallery to be redrawn by using the setGallerySize() and showGallery() Juicebox-Pro API methods. (Please note that this requires Juicebox-Pro.)
However, this may be difficult to implement within a WordPress environment where the pages are created dynamically.
It would require more than just a modification of the WP-Juicebox files as the call to the API methods would have to be placed in the links to the galleries.
I hope this points you in the right direction.

If everything was working OK and now it is not, something must have changed to cause this problem.
Can you remember making any changes to your computer between it working and now not working?
Did you install any other software or updates which may be causing the problem?
Are you able to use System Restore to wind back your system to a time when the problem did not happen?

Do you mean that the 'New Gallery' and 'Open Gallery' buttons are ineffective or is there some other problem?

Try running JuiceboxBuilder-Pro with administrative rights (right-click the shortcut and select 'Run as administrator').
If this does not help, try the following.
Uninstall both JuiceboxBuilder-Pro and Adobe AIR and then manually delete the C:\Users\username\AppData\Roaming\Adobe\AIR\ELS\JuiceboxBuidler-Pro folder (as before).
Now, reinstall both Adobe AIR and JuiceboxBuilder-Pro using the right-click 'Run as administrator' option (rather than just double-clicking the installation files).

If this does not help, create a new Administrator User Account and try installing and using JuiecboxBulder-Pro from this account/

Hopefully one of these suggestions will help.

It looks like your current WordPress theme may be using some global CSS rules which are breaking the layout of the gallery.
Also, when validating your homepage with the W3C Markup Validation service, 142 errors and 34 warnings are reported so it looks like your theme is not generating valid HTML code which may also be contributing to the problem.
Try upgrading your Nemesis theme to the current version (v1.5.2) to see if this helps.
Otherwise, try using a different theme to confirm whether or not the Nemesis theme is responsible for the HTML errors on your page.
Even if the HTML are fixed, the problem may still be due to global CSS. There is no way to sandbox elements on a web page and global CSS rules may break plugins (such as WP-Juicebox) which have no option but to inherit these rules.

I understand your request for a simple 'Mail' Button Bar button but, working with what is currently available, the following workaround may suit your needs better (though is a little more complex that my first suggestion).
It uses the 'Open Image' button (displayed on the Button Bar) so if you currently use this button for its intended purpose, you will not be able to implement the following.

• Set every image's linkURL to 'mailto:email@address.com'.

• Set every image's linkTarget to '_self'.

• Set showOpenButton="TRUE" in your gallery's XML file.

• Change the icon for the 'Open Image' button using the technique in the Using Custom Icons support section.

• Change the toolip text for the 'Open Image' button using the languageList configuration option (so as not to confuse users).

The imageShadowColor configuration option in your gallery's XML file is currently set to:

imageShadowColor="rgba(0,0,0,1
0
0)"

The 4th parameter of the rgba(r,g,b,a) value should be set to 0 for the color to be fully transparent so change it to the following:

imageShadowColor="rgba(0,0,0,0)"

For others reading this thread, you can remove the drop shadow on the main images by either setting imageShadowBlur="0" (in JuiceboxBuilder-Pro's 'Customize -> Main Image' section) or by setting the opacity of the imageShadowColor to zero, e.g. imageShadowColor="rgba(0,0,0,0)" ('Customize -> Color').
The 4th parameter of the rgba(r,g,b,a) value is the opacity (the alpha channel).

There are two separate issues causing your problems, both of which look to be caused by global CSS on your web page that the Juicebox gallery is inheriting.
It looks like your web page uses the border-box model for all elements on the page (which affects the icons and thumbnail frames being offset) and sets a global font (which overrides the main image navigation buttons).

Try adding the following CSS to your gallery's 'jbcore/classic/theme.css' page which should solve the second issue (with the main image navigation buttons):

.jb-navigation .jbn-left-button, .jb-navigation .jbn-right-button {
    font-family: juicebox;
}

With regard to the first issue, try searching through the CSS on your web page for an entry such as:

* {
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

If you find such an entry, change it to:

body {
    -moz-box-sizing: border-box;
    -webkit-box-sizing: border-box;
    box-sizing: border-box;
}

... and then add the following CSS to your gallery's 'jbcore/classic/theme.css' page. This should fix the problem.

.juicebox-gallery a, .juicebox-gallery div, .juicebox-gallery h1, .juicebox-gallery h2, .juicebox-gallery h3, .juicebox-gallery h4, .juicebox-gallery p, .juicebox-gallery span, .juicebox-gallery u {
    -webkit-box-sizing: content-box;
    -moz-box-sizing: content-box;
    box-sizing: content-box;
}

Bug reports have been logged for both issues so the gallery elements affected should hopefully be better protected against global CSS in the next version of Juicebox.