I tested every possible combination with aguf and my other addons (all off or some switched on) but everytime it stopped working after using my homestone or it suddenly stopped to work in a fight or when I was riding through mobs.
Two things I have to test: aguf without health fade and distance check and to delete my aguf.lua in the WTF-folder.
Perl Classic doesn't have this issue, but I really prefer the style of aguf.
The problem is caused when someone joins your party/raid while you are in combat. The only solution I can think of is have it update the frames again when the player leaves combat and or don't try and update the frames at all while in combat.
I also have this problem, but sometimes I cannot click on 2nd or 3rd party member as well. I tried to switch leader to see if this would fix problem, but it didn't work. So its just not the 4th member but anyone is fair game to get this bug for me
@andreasg: Your last update yesterday works fine for me but I didn't put ag_uf to the acid test yet.
My other problem: I think I found out that "AuraMap" is causing the problems with targetting.
I can't imagine why it does that but could you take a look at it and maybe protect your unit frames from being damaged by this/other mod(s)?