That fixed it for me, too! Thanks!
At some point a couple days ago, I stopped being able to update icons or banners on communities. I've tried everything I can think of on my side, including appointing a friend as a mod, who was also unable to edit the images.
[EDIT] I had both English and Undetermined selected somehow, and as per user suggestion I fixed that, and it worked! I can now update images, I just had to select ONLY undetermined.
Done, thank you very much again for your help!
Those are actually not GIF files, they are *.webp files. I'm not sure if GIF format is supported, honestly.
That's a good suggestion, thanks! ...unfortunately I already tried that, up to and including deleting the current images completely to just start from scratch, and the UI won't let me. I even tried deleting the community - and learned that there's really no such thing(?) When you delete a community apparently it stays in the database as a deleted community, and only you can un-delete it. Not sure if that's a temporary thing, or if it's permanent, but in either case deleting that community didn't allow me to make a new one with that same name. All I could do is un-delete it, and my problem persisted.
You can convert most GIF files to webp, which lemmy can use, and those are MUCH more efficient in terms of quality for the space used. But for some reason if you try to upload a GIF to lemmy it turns it into an MP4 file, instead. It's generally much better to convert to webp first, or better yet create in that format to begin with.