People falling through stairs/the ground...

I don't know what mod is causing this, I have so many. If I had to guess, walking speed sped up or having everyone in the party, but I've had those for a long time and never had this issue before.

It's genuinely making the game unplayable, I spend so much gold bringing people back from "perishing in a chasm" (the floor) and time fast traveling to get half the party unstuck from under a staircase. Is anyone else experiencing this even if you don't have a solution?