Have noticed that, AOE helps there.

yeah i've noticed this as well, they can only be killed with AoE when they become untargetable.

I remember them being a bit weird with my warrior, but with a pistol I basically have to walk around with a horde of them following me, which wasn't too bad until I got an elite group, and died 3 times only to discover that basically resets the zone when I was pretty much at the end.

I had the same problem last night. Everything was going great until I got swarmed by those cave bats. I was able to kill a few with my bow early in the cave but, the further I went in, the more I ran across ones that I couldn't target. Some have suggested AOE spells so I will try some others. I did try using a spell with multiple arrows but that did not work either. At one point, four of them surrounded me and I couldn't move out of the circle. Not even my evasion ability would work. I had to get killed multiple times by them until I was able to spawn back at the last checkpoint. Porting into town didn't help either because I just spawned back in the middle of the swarm upon return.

Same here, running a spell caster with a staff makes these a lot easier as the staff projectile default attack hits multiple enemies. And assuming no other enemies are around I run around them with frost nova. I have also noticed that if I hold shift, and force attack without moving, I can occasionally get a lucky shot and kill them too.

I am also having this issue, while not game breaking it is kinda anoying. AoE dam helped get me past them.