If you can't butcher, it's because there's a conflict between the original Medieval Overhaul 1.3 and the unofficial 1.4.

This conflict occurs because I use the same packageID as the original one, so that all mod dependencies are given. Unfortunately, this means that things seem to be loaded from the old mod even though you haven't activated it - at least that's the opinion in Discord.

To fix the bug, you have to unsub from the original mod until the official update of MO.