There is also a known bug that I am literally submitting a fix for as we speak: Basically when Convex Decomposition is calculated for large objects (larger than 50, by 50, by 50) there is a chance that the ConvexDecomp will randomly create a point OUTSIDE of the shape to include in the Convex Decomp. I noticed that some FBXs that I import from blender are pretty big.
If you’re relying on wheels imported as MeshParts to collide properly, this would be one of the issues.
I’ll have a fix for this shortly, but THIS thread needs more details about the bug report. Please follow the guidelines here:
EDIT: Didn’t mean for this to be a post aimed at you Extuls, just in general at this thread.