"unkillable" critter in a greater rift

[mouser2k 0]

i was soloing a greater rift with my sorceress the other night when i noticed a ghostly mob attacking me. i couldn't target it with spells, aoe's didn't touch it. i had to zone to be able to town portal after finishing the rift. Who else has seen this, what's the story?

[Arkpit 101]

It is not uncommon for monsters to get stuck in "limbo" where it looks like it simply never died and you can't touch it after that happens, does that sound familiar?

[Discord 2]

I see this sometimes with angry chicken.  If I blow up a monster badly enough, it sometimes turns into a ghost - just stands around doing no damage and is unkillable, but is annoying because it keeps you from returning to town or porting out.  

I think it's some kind of game bug.  Same thing used to happen in Diablo 2 - a sorc could use TK to kill them, otherwise they couldn't be affected.  

[mouser2k 0]

thanks for responding. yeah, discord, only this one hit kinda hard. suprised i never saw it in diablo 2.