Well, I decided to play Auntie Helper Elf Mistletoe and tried three ways to change my Avatar and it didn't work for me either.
The signature section is fine, but I received the same debug error when I tried to upload from my computer.
I received a message indicating that my profile had been successfully updated when I place an URL link for an Avatar (within the permitted pixel range) and did it a second time with a successful message, but when I checked all that was there was a red X where the image should have been.
I deleted the existing image and tried again with the same outcome.
Might be a problem. Anyone else want to give it a try?