Here is a highlight from my stream in the exact moments these bugs happened (both happened during the same moments): https://www.twitch.tv/videos/367560692
Not sure what caused the zombies to suddenly start appearing inside the house while both doors were closed, but we were completely overwhelmed. The hands bugging out with the block didn't help and we got destroyed. From what I noticed, they bugged out as soon as I used the hotkey to swap to the pistol while walking backwards (attempting to block zombie attacks). Could be a bug in the code in the functions controlling the block and weapon swapping, perhaps the weapon swap function is overriding the context for the melee block function?