Issue: Enable AJAX previews of wiki content Not working

I copy and pasted the AJAX preview Javascript file from your site and it works on my site. I see that you are also using Google Pagespeed, which adds an extra layer of processing to Javascript. Please try temporarily disabling it and see if that has any effect.

I didn't try disabling pagespeed yet...

I noticed that under the path js/vw/vw/min there is no such file, which is why nginx won't serve it (404)

I also checked that the lightbox.js doesn't seem to be bundled with the vaultwiki zip file?

Hm... So in the VaultWiki code, lightbox.js IS added to a list of possible Javascript load-on-demand files, and that file list is generally output to the browser. However, (text-search confirmed) there is no code in VaultWiki that actually triggers that file to load-on-demand. So I am not sure where you are seeing this file fail to load, or what would make it try to load. I cannot find an example on your site.

I also don't think it is related to the AJAX preview issue since AJAX previews are not working even on pages with no lightbox error (as I mentioned I can't even find a lightbox error). From what I can tell, it just seems that some code is not running on your site. It is possible this is due to timing issues or small code changes introduced by running mod_pagespeed. I am not sure that mod really provides much benefit on your Javascript under XenForo, since both XenForo and VaultWiki provide minified scripts anyway, and the scripts are generally already as deferred as possible in their design. From what I can see, you might be saving network latency on 1 file in total, which may not be worth the added execution time and lower reliability overall of using mod_pagespeed in this way.

I tried disabling mod_pagespeed and still get same issue.

I had a check in console again, and just before the lightbox failure to load there is another:

So something seems a bit broken there... Should not be due to pagespeed, wondering could it be CF some rocketloader messing with it?

Please message me a link to the wiki page where this is occurring.
Your mention of RocketLoader reminds me that RocketLoader was historically bad (https://www.vaultwiki.org/issues/5716/) and we force-disabled it for a number of versions. We later allowed it to come back on, but if you are having issues and can confirm it's RocketLoader, then we may have to block it again.

I've noticed that the preview actually loads, but is invisible due to having a non-existing z-index value... Even setting it to 1 helps, but probably good to make it a higher value....

Still the image in the preview/tooltip are broken and doen't load, likely related to that undefinedhttps://.... error shown above

Fixed the z-index in the next release. The value should always be at least 100, but it will try to calculate the z-index of the link being hovered, and make the z-index of the preview-wrapper higher than that.

I am still analyzing the additional information about the images and undefined error.

Fixed the loading of the missing lightbox.js file in the next release. The problem was actually something else -- that after AJAX, it was trying to load every Javascript file in the trigger list, rather than only files that were actually triggered by the AJAX. Since there are no triggers currently in use for the non-existent lightbox file, it should no longer attempt to load. The name remains in the list because it is reserved for future use.
This change has the benefit of reducing traffic and bandwidth whenever something AJAX happens.

For the undefined icon image in preview, if using the unminified Javascript files, in js/vw/vw/base.js, find:
Replace with:
If using the minified files, in js/vw/vw/xf2/compiled/base.js, find:
Replace with:
You'll have to refresh the page with no browser cache and possibly expire the file in any other static file caches you may have, such as a CDN or CloudFlare cache.