It looks pretty similar to an issue I was having in the past. I asked Luiz about it and he had me get the latest version of the tool from GitHub: https://github.com/sideeffects/GameDevelopmentToolset/tree/Development
I think that had solved my problem (but introduced a new one I can't remember) a while ago.
The problem, at least for me, that I had discovered was that combining meshes in Maya that were being used in the Houdini simulation, caused the tool to no longer write to the meshes vertex colors correctly on export. For the rigid body simulation the vertex colors represent the pivot point for a chunk of vertices. You'll be able to see if that's the issue by checking vertex colors on your exported mesh. If each chunk is a different color you that may not be the issue, but if the vertex colors are all the same (I think white) on the exported mesh, then that's the problem. Either way getting the latest version of the plugin is worth looking at.