When I upload a new profile picture it tells me the changes to my profile have been successful but nothing changes
It’s a tad wish-washy so this might help
Always reset your picture to nothing before changing it by clicking ‘Use default avatar’ come out of your profile and re-open it, apply your new avatar image and it should work.
Optional:
Try to keep images less than 500x500 and dimensions in sync look better (64x64, 128x128)