I've been using Next Gen for over 5 years.
I upgraded to WP 3.6 but it caused issues with my site, so I rolled back to 3.5.2. I re-installed Next Gen 2.0 instead of the latest version due to its requirement for WP 3.6.
Now, the Edit Thumbnail feature has stopped working in 2.0 and is stopping me from adding much needed galleries to my posts.
The area where you would edit the thumbnail has a broken image link in it and does not display the functionality to edit the thumb.
Can someone tell me how to fix this please.