Well I've found a temporary solution, though it's less than ideal and is a workaround.  Since the url is appended with "#expanded" when the gallery is expanded, adding an event listener to detect changes in the hashtag and using this to force a reload of the page when exiting the gallery (when "#expanded" is removed from the url and window.location.hash becomes the empty string) covers the occurrence of the issue:

window.addEventListener('hashchange', HashTagChange);

function HashTagChange() {
    a = window.location.hash;
    if (a == "") {
        window.location.reload()
    }
}

This can then be surrounded by additional javascript to add the event listener and/or execute the function only for non-iOS devices.  Since I do not force a splash page and it therefore shows only on small mobile devices, the desktop and larger tablet experiences will not be impacted.  Older desktop browsers that don't support "hashchange" will also not be affected.

I view this as a stopgap, however.  It's sloppy and only works consistently when using the phone's back button to exit the expanded gallery, which means that the showExpandButton option must be explicitly set to "FALSE."

I hope the developers tackle this issue in a future update.

Is there a way to add an event listener to detect when the user exits the gallery?  Setting expandInNewPage="TRUE" isn't appropriate because it causes a poor experience on the phone when swiping through galleries, and the custom javascript used to embed galleries on my site's pages was designed to deal with the variable height problems based on screen resize (or, in the case of phones and tablets, an orientation change).  All works fine on the desktop, but it's still breaking on phones and it seems that the only way to solve the problem is to force a desktop style layout across the board.  None of the solutions proposed are taking care of the issue, and the only thing that seems to work is hard coding a fixed width and height (not at all ideal on a responsive webpage).  Given Android's dominance of the market, if there is no workaround for this I will have no option but to remove Juicebox altogether and look for an alternative.

There has to be some way to fix this problem.  Using the recommended embedding method and eliminating all other script and html, yet still having the issue, seems to indicate that the issue is with Juicebox itself.  Is there a fix for this in the pipeline?  Also, are you seeing what I am seeing, or should I post screenshots?