Hello MarkJW,
I found a way to work:
HTML Code:
<if condition="!is_member_of($bbuserinfo, 1, 3)">
<a href="member.php?$session[sessionurl]u=$bbuserinfo[userid]"><img src="$navbar_ava[0]" alt="<phrase 1="$bbuserinfo[username]">$bbuserinfo[username]</phrase>" width="48" height="48" border="0" /></a>
<else />
<img src="$stylevar[imgdir_misc]/defaultavatar.gif" alt="Avatar" width="48" height="48" border="0" />
</if>
This code work, but need to be install a plug-in:
https://vborg.vbsupport.ru/showthread.php?t=83053
If you do this it will show the avatar in your header.
Hope it helps you!