>>528094640
The first part sounds like the issue where your internal position is clipping through the geometry, probably under the floor, and you're considered stuck and shit. That's pretty bad. The unable to cast shit is probably coming from having no line of sight according to game internals. This is related to the same shit that breaks auto-follow on companions. I don't know of a good way to fix it in vanilla. In theory, you could modify your coordinates in the save file but I wouldn't know if it's just one set per character or if there are multiple (e.g. world position, model position, auto-follow tracking information, etc.) so I can't offer any better help than that.

Is this all in one session or have you reloaded, or had the host do a full game restart yet? Did it continue after that, or did it get fixed for a few mins before starting again? Did you have any wacky jumps/clipping/explosions/elevator mishaps flinging people into weird corners around when it started?