Also at the same location Zombies spawn on the slope (to the SW of the entrance) and fall to their deaths

Had this issue with rog, unable to gain access without vaulting.

My friend got stuck in the floor last night

Yeah, Zub isn't working the placement is really too high to enter. You can vault and get "access" to get 1st floor but you are under the floor and can't see the loot which are also under the floor. And while you are under the floor you can't try to vault to the stairs to get access to next floor.

I was able to vault into the first floor, then vault a couple times to get "out"of the floor and use the stairs.

I had the same problem trying to get into Devil's Castle (up the stairs) the other day. Tried to read about it online, and couldn't find anyone else complaining about it. I tried vaulting over the raised platform in Zub, and managed to clip inside the floor. Tried the same thing to get up the stairs once inside, and clipped inside the stairs... Scared me, in DayZ mod I would have expected the CRACK of my legs breaking.

added some Screenshots

Zub, and Devils are both too high, even thou you can get in Devils, the loot is in the floor not ontop of it, so you can not loot these locations unless its a tall loot like large boots and packs

I did gain access to Zub in 0.28 and when trying to go up the stairs I simply walked into them.

Added my screenshot.

Confirm that.

Same here in Zub castle, but the same thing happened when I tried to enter a supermarket from the back. Can't remember the location though.

confirmed. a couple of the castles need vaulting to access and even then the loot is inaccessible and visible in the ceiling above you.

Loot still stuck in the floor at Devils. I was trying to look at some boots and fell off the first level of stairs (Maybe 3/4 of the way up) and fell to my death on full health... Now I'll never know what the loot is like.

Confirmed

Hey guys

This issue is fixed on the internal server. Please wait for a new patch.

Thank You for reporting this.