I've noticed that whenever a user uploads a new avatar, you have to clear the cache in you browser before you can see it. It's kinda annoying, because some users contact me and say that it doesn't work whenever they try to change their avatars.
I've made a small video about it. Whenever the avatar updates, it's because I clear the browsers cache (Ctrl+F5).
If I remove my current avatar, the default one is showing right until I reload the page. After the reload, it shows my old avatar.