I saw the same question posted in July and there was not one response.
Is there really no answer? Seems like a hole in the software.
I think it is a hole in the software. I searched the Knowledge Base but could not find an existing bug. Have you reported this to your VAR?
FWIW, my attempt at reproducing the issue below:
Non broken view:
Center of Mass is unselectable.
Retrieving data ...