This happened on one of my servers, i fixed it making a new one from cero and it was fixed; if is in singleplayer try to reset the map (maybe this work)

I don't understand. I'm having the same problem. What do you mean you made a new one from cero? What is cero?

I had this problem too, and after a painful amount of time trying to fix it I found a solution. Try to copy the entire tales of terror folder and paste it in
C:\Program Files (x86)\Steam\steamapps\common\Unturned\Servers\[something]\Workshop\Content

Rallve this problem only occurs in my servers, I alrdy tried but still no luck since i put the map into both the map and content folder.

FIX: SUBSCRIBE TO THE DEVKIT FOR THIS MOD

Hello Radical IsLlama. I subscribed to the devkit but that hasn't fixed this for me. I've left a lot of dead bodies on the floor in Hades.

Subscribing to the devkit will break the mod, if you're falling through the floor in MP then you don't have the map in the contents file as well. If you're falling through it in singleplayer, only thing I can think of is that your computer loads so slowly you fall through the floor before the building is loaded. I suppose you could try upping your render distance.

You need to put the mod in your server content file.