After the software upgrade, this happened to all "old" accounts that aren't paid members.
When the forum first started there was no paid membership and anyone could have an avatar and/or sig line. When we migrated to this software, most of the avatars came with it. When we instituted a paid membership level, avatars and sig lines were assigned as a privilege of paid membership only, HOWEVER if an "old user" didn't do anything to their existing avatar, it was not deleted.
Somehow this new version of the software made a change and any unpaid memberships lost their avatars and sig lines. TTBOMK this was not done intentionally, it sounds like the new version did a "clean up" under the rules of how the forum was setup.
If you want an avatar, sig line, participation in group buys/group dinners/group shoots/etc. you can pony up $19 and join as a paying member. Details are in the Announcements group in the forum index.
Hope this explains it.