I have Catchmoon with +2.5 punch through. Nothing bad, nothing unusual. Until i shoot an enemy that too close to me, they dont receive any damage at all. This happen a few times. Then i decided to test it on Simulacrum.
I shot them from 1m-2m range and they received no damage at all, but more than that, they got hit. But sometime, this bug still exist even if the enemy is more than 2m, not too far tho, but more than 2m. I remember this because i had to shot Nox but he got no damage at all.
I tested Tomfinger with punch through mod, it doesnt have this bug.