I have a hatch in skyrim connecting to a single-cell dungeon.
Everything seems ok when first entering, but
if I leave and re-enter, the following bugs occur:

portal and/or roombounds seem to move and cause some views into the void around the portal positions.
(they are always perfect before re-entering).

I have leveled monsters that teleport into different areas of the dungeon after re-entry,
and seem to huddle in a corner. They move around a little but don't want to chase
me. (the first time entering they seem fine)

I also have some custom enemy actors that inherit some traits from leveled vampires,
but have different appearances/stats and don't cause vampirism.
Sometimes when re-entering they seem to turn into a full regular vampire.

Anyone have experience with these types of problems?

I've heard of issues with navmesh upon re-entry, but those other issues are new... Quite disappointing how many issues are in esp files

Yeah I read about the navmesh bug but I haven't moved 2 cells away so I haven't seen the actors freeze altogether.

I think I just fixed the teleportation issue. It seems I had a stray bit of navmesh that wasn't connected,
and that was the exact point everyone was teleporting to. Now they seem to be ok.

I gave up on the portal and room-bound issue so I removed them.