Images are not showing up after uploading to new gallery

I have setup 4 galleries with no issues at all. I have tried setting up a 5th gallery and I can upload the images fine, but when I try to view one that has been loaded I get a grey screen with the word ‘LOADING’ in the middle. Nothing happens.

Also the thumbs are not being generated. Not sure what the issue is… any thoughts?

See this screenshot: https://i.imgur.com/1jybHtF.png

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