I checked my testsite and I have the same problem:
For a user where the Avatar is a 'standard one' from the forum, it shows in the comments. I am using an uploaded avatar that is NOT displayed in the comments.
The link used in the comments is that: https://test.fjr-club.nl/avatars/
, it seems to link to the folder, not the actual uploaded image...
I also checked it in 1.3R and there it was working fine.
On the site: SSL with Image proxy fully enabled...
Deactivating the image proxy makes no difference: problem stays