Arkngthand, Heaven's Gallery has a very bad glitch where when you enter you are vibrating back and forth and cannot move. When I toggle collision I also see the NPCs inside are vibrating back and forth and cannot move. Arkngthand is where you go to get the Dwemer puzzle box in the main quest, so you should be familiar with it. Heaven's Gallery is a certain room of Arkngthand and you will see the glitch when you enter in Morroblivion [v066].
You really need to fix this because it looks terrible especially when Arkngthand is a place everyone is familiar with.

I see this other person has posted about it here:
https://morroblivion.com/forums/morroblivion-problems/soluti...
I don't know what is causing it, but for the next official release of Morroblivion this has to be fixed.
This is fixed internally.
The issue is still present in Morroblivion [v067] which I downloaded here:
https://m.morroblivion.com/forums/morroblivion-development/m...
I don't doubt you can fix some of these problems. My concern is there can be some laziness where the fix is not merged into the main build. I downloaded Morroblivion [v067] because it is supposed to fix corpses constantly falling through the floor, where you can't even loot them, which it seems to have fixed.
Aside from the extreme bugginess of Morroblivion I give it 10/10 as far as a game. Frequent crashing to desktop, corpses falling through the floor, and this Dwemer ruins bug are the main problems I have had playing the game.
v067 kept corrupting my saves and crashing to desktop when loading different saves, so I went back to v066 and tried the following fix for corpses falling through the floor:
https://morroblivion.com/forums/rel-morroblivion-v66-model-u...
It does seem to be working to fix corpses falling through the floor in most of the situations where it was occurring before, but you can still get it to happen in some situations such as with Snowy Granius if you kill them on the bridge near Arkngthand and not over the dirt. Also in the Fighters Guild of Balmora if you use the kill command on the members they fall through the floor. So it hasn't fixed it 100% but it is a big improvement.
The fix that other person provided for the Dwemer ruins does work but it isn't something the consumer of the mod should have to worry about. It's a real headache Morroblivion due to the technical issues and it's hard to recommend because of that.
Interesting, version 67 will require new saves, it just updates way too many scripts.
Well, The experimental build is in pretty bad shape, it's a few years outdated by now... I have not released anything newer, but the actual up-to-date build has over 100 additional fixes and is in working order.
I'm looking into fixing Universal Cast When Used, So I can push out a Version 67 maybe RC build.
Another Model Fix was backported, this will fix additional cells with bodies falling through the floor.