Troubleshoot muscles

Can I still use earlier cMuscleSystem 1.xx files?: Due to some technical changes in the core functionality, it is necessary to convert/update files from earlier versions of cMuscleSystem before they work with Maya Muscle. See Re-Initialize setup data on Maya Muscle.
When I reference in a rig with muscles, I get file load errors.: You may encounter this issue as you test your rig or scrub time to test Jiggle in your rig file. Try deleting the Jiggle cache for all muscles: Delete a muscle Jiggle cache. This removes Jiggle cache information from the rig, so that it can be cleanly set in the referenced rig animation file. You may not see this error until you animate and reload the animation file with the referenced rig.
Disconnecting a muscle takes a long time. Is there another way to do this?: Yes. The Disconnect menu item attempts to first zero out any weights to the muscle or node you are disconnecting, which can take a long time. To speed this up, you can do a manual disconnect.

To manually disconnect muscles

In the Muscle Paint tool, select the node you want to delete and zero all Sticky weights (flood to 0).
Delete the muscle or node, or disconnect its connections to the deformer.
Select Muscle > Skin Setup > Auto-Fix Deleted/Missing Muscles from the main menu bar. This properly finalizes the disconnect.