I did add your bug to the bug tracker and the number for your bug is #8798 and this bug can be related to the bug number #8792.That bug is probebly fixed all ready,if this is the same place.
took a job delivering to Lillehammer but when got there couldnt deliver because my truck sank into the ground, managed to get truck and trailer rescued, repaired it and headded back to ww.logistics and entered the yard via a different entrance and the truck sunk again so abandoned the job. the trailer disconnected and truck went into freefall.
Regardless of other mods being used or not, this is a known issue: Lillehammer, Norrsken, falling through the ground
The Norrsken company comes up as W&W Logistics if you have the ProMods TCP installed.
The issue has been fixed internally and will be out with a future release of ProMods.