Looks like the letter avatars (software’s default) disappear. Don’t know if it’s only me that have problem in visualising that or it happens to someone else. Please note that custom avatars are not affected.
The forum software server (not our own) serves those avatars. I notice that from time to time their server acts funny and then returns to normal.
It’s fine now.
The avatars are gone again.
I see them.
Ah, but I see them in Firefox. I don’t see them in Chrome (both Linux).
I have Firefox, so this adds up!
Try clearing your cache. I tried in Firefox, Chrome, Edge, Safari and the avatars are showing ok.