Hell horse suffocated in rock enter in the mine

[Annyil 189]

I was leading a hell horse when entering a mine with a rock mine door.
Hell horse was branded, not tamed and being led by a Fo's priest so not aggressive against being led.
As realized later the hell horse got unhitched so tracked back the location using get direction and checking the logs.
When I arrived back to the mine entrance it was lost I've heard the death shriek of the hell horse and could no more find it with Get directions (cannot find the animal, it was here a minute ago)
The corpse did not show up nowhere, but about 10 minutes later appeared in front of the mine entrance (I have passed there a few times in the meantime between heard to die and see the corpse)
The corpse shows the cause of death is suffocation in rock.

 

UPDATE: The hell horse was kindly restored by GM team (thank you!). The next moment the hell horse on lead unhitched in front of the mine door when I entered the mine - visually I could only see the flame on its head under the cobblestone tile in front of the mine door and could not rehitch.
Fortunately this time the hell horse entered the tunnel and I could put in on lead in there.

 

 

Edited January 7, 2021 by Annyil
update

[Delone 215]

Sounds like I may be lucky I didn't stay in mine too long with my vanished horses as reported over Here