it's short. To add squash to the CAT rig, you create max bones, Position/Orient the Root to the CAT joint you want squash on, Position/Orient the Tip to the next CAT joint in the chain. Then in Bone Tools Turn off Freeze Length; and enable Squash for the Root.
Finally!... the thread has fell apart. Time to post Cats, its been a while since my last cat, so I'm allowed. Anyhoo, as soon as Part2 is posted this thread will return to an "opinion debate". EDIT: funny cat gif removed....A sad day indeed.
CAT is a 3ds max component, not blender's. sadly, no idea here about the issue at hand. CAT does display some odd behavior at times though. it may be worth trying to import the rigged model into a fresh scene or even recreate it by transferring the CAT rig preset and animations?