Hello @LHSimulations
With MSFS 2024 native package, this can be handled by enabling “Ground collision” in your ground object Blender material properties:
In the case of 2020 packages, this has not been addressed yet and is tracked through this already existing report: Erratic behavior of simobjects on collision meshes - [MSFS 2024] Bug Reports / Airport & Sceneries - MSFS DevSupport
Regards,
Sylvain