Uploading new profile picture - keeps defaulting to old pic

I've tried unsuccessfully to update my profile picture.  It's in a jpeg format however it seems almost as if my old picture is hardcoded because I can delete it, leave the edit profile pic section, come back and try to load new (unsuccessfully) then the old pic re-appears.

I've tried searching the forums however the only thread I found was from many years ago.

Thanks.