Dead bodies prevent you from hitting
With the body of a NPC on the ground between you and someone else, it is impossible to hit. No "miss" sounds, it's like the hits don't register at all and the body "absorbs" all your swings above it. Your enemy on the other hand can still hit you. I tried it with creatures too, but could not replicate it, so it might be just NPCs causing it.
Positioned like this, you can swing your weapon but it won't do anything at all.