I'm having this problem also. It's really annoying especially when fighting the bosses. It's no fun when they don't fight back. It's only happening to me on the PC version. Never had this problem on the 360 version.
Update:
Looks like the Magic Duels mod is the main culprit, at least for me.
Bizarre enemy behavior
in Skyrim LE
Posted · Edited by NoZaku
I'm having this problem also. It's really annoying especially when fighting the bosses. It's no fun when they don't fight back. It's only happening to me on the PC version. Never had this problem on the 360 version.
Update:
Looks like the Magic Duels mod is the main culprit, at least for me.