Thank you for this post. Unfortunately I can't help because I currently have the same problem.
I have already tried it with a compact <500kb-version of the profilepic which also didn't work because of a picture-size-limit I've heard about although it seemingly only applies to video-thumbnails and not profilepics and -covers.
And with my profilecover-image it's the same problem although I haven't tested it with a <500kb-version because I think it wouldn't look so good.
I also think the problem has nothing to do with the used browser because I already tried it with Brave, Chrome and Firefox.
Thank you! I hate to see it happening to you, but glad I'm not the only one lol.
I was thinking maybe it was because i used steemconnect to link them at the beginning. So I then tried to used my private posting key following the help on Dtube
Unfortunately this did not work either.
If you try it and it works for you, please let me know.
I've already tried it with the private posting key but unfortunately it also didn't work for me. But for my first log-in into DTube I've also used steemconnect instead of the key. Maybe first using steemconnect instead of the private posting key could be an explanation for our problems, but I'm not sure.