Our site was experiencing missing attributes between cad objects and associated wtparts. We are using Windchill 10.1 m010. Windchill 8.0 used to force an implicit check-out of the cad object to the workspace when auto-associate was invoked. Windchill 10.1 doesn't do this. You have to check out the cad objects and then perform the auto associate in order for the cad attributes to pass to the wtpart. This was noticed with the attributes mass and material.