ToME: the Tales of Maj'Eyal

I ran into this repeatedly on Linux 64bit in version 1.6.5.
I have not yet dared to try to reproduce it in 1.6.6 because I like my current character and encountering this bug regularly led to me dying – I don't want to die!

I saved while being in a vault.
Then I exited the game.
When I started the game again, I was still in the vault as expected.
But when I took the stairs out of the vault, I did not enter the level I was on before entering the vault, but instead I entered another vault level.
I did not enter this new vault on the stairs but instead somewhere else in the level: Sometimes right next to enemies or even in some of the secret/secluded areas that you have to dig into.

This happened on multiple characters on multiple occasions.

Everytime I fled from a vault just to enter another vault right next to some fresh monsters I was pretty surprised – and dead

Do you still have the savefile that can exhibit the problem by any chance? I'm trying to hunt taht bug but I kinda need a save:/

it likely is a problem specifically with hidden vaults, but you knew that

I don't have a current save around but I'll have look through my backups if I might have captured something.

When I encounter the next vault in 1.6.6, I'll save-scum and try to reproduce it.

(And as mentioned, I mean the vaults that are an extra level ("greater vaults" in the wiki), not the small parts of a level with the locked door.)

I have found a save from last week in my backups with the screenshot looking like a vault.
I moved it to my save folder and loaded it with version 1.6.6.
When I walk up the stairs form the vault I entered another vault at a random location.
So it is reproducible, even with 1.6.6

I have upload the whole save here (it is too big for a forum attachment I think):
https://www.cgarbs.de/tmp/vault_save.zip
The download link is valid for the next 2 weeks.

(edited post: first I wrote that I could not load the save at all, but I just messed up the directory name …)

I got my current character in the main game to Vor Armory and found the first hidden vault there.
I did not have any problems saving there.

The current character is running on version 1.6.6, so this problem might have been fixed by the upgrade from 1.6.5 to 1.6.6.
Or the problem only happens in the Orcs addon (an information which I just realize was missing from my initial report - sorry).

With 1.6.6 in the main game I also encountered no bugs when saving in a vault.
So either 1.6.6 fixed this problem or I had done something really strange in my 1.6.5 game prior to my problems that I can't reproduce any more.