Hi,
Problem was previously reported and discussed on this thread.
https://community.auctiva.com/eve/forums/a/tpc/f/838609941/m/5851072503I haven't seen any update of the problem by Auctiva.
Note my observation that .GIF was being converted to .jpg and .gif stores as .gif, but with transparency and animiation removed, i.e. only a single frame.
I checked the product website for the new uploader they are using, and it does have that drawback. My suggestion would be to restore one simple upload for .gif use ONLY as a workaround. I think the consolidation on the uploader page was when this problem occurred, as my use of the old HTML uploader was probably the last use (that worked).
Danno