[Plugin: NextGEN Gallery] Albums – Edit Album – Preview Thumbnail image not loading

I’ve been having this problem for a long time now, I can’t assign a thumbnail image to my albums. The wheel loads forever, drop-down list doesn’t show. I’ve been waiting for new versions to come out but this problem still isn’t fixed. Can someone please help?

https://www.ads-software.com/extend/plugins/nextgen-gallery/