Importing a building mod FBX model with a "BSP" mesh AND portal planes (e.g. PRT_01) always results in Workbench crash if "Force Create Portals" import option is NOT checked (which is required to be unchecked according to the documentation).

Crash does NOT occur if there are no portal planes (e.g. PRT_01) in the FBX model.

I followed these instructions: https://community.bistudio.com/wiki/Arma_Reforger:FBX_Import#BSP_Geometry