When thralls and tames are hit with the spiders web attacks that cause cripple, it causes thralls and tames to bug out and stop attacking completely. I think the same goes for the undead hyenas and any other creature that can cause cripple. Spiders in H5 and Undead Hyenas at sinkhole.
The only way to fix this is to swim across a body of water . Once you reach land the thrall/tame tends to work normally again.
An annoying bug. Might be worth checking with all creatures that cause cripple.
You can recreate this bug by having a creature be hit with an attack that causes cripple. You’ll know if it works because even after combat, your thrall/tame with be standing in “attack stance” even with no enemies around.