Kelly and I talked about this in a tech support function.
What they were trying to do was graph a gray profile. Because a gray profile literally has no color information, it could not show up in a 3D Lab graph. ColorThink was crashing at this point, but what it needs to do is give a warning that the attempted procedure is out of the bounds of what the grapher is supposed to do. This has been corrected in a later beta.
The other functions of ColorThink Pro (Profile Manager, Profile Inspector, etc.) continue to handle gray profiles just fine.