When changing to a different rig in Rig Manager, clicking “Apply”, “Save”, “Close”, etc. doesn’t work. The new hardware connected to the alias doesn’t control the rackspace. If you then close GigPerformer and re-open, the new Rig selection will work.
I found this out because I had been trying unsuccessfully to set up controller aliases. An Internet search led me to a post on the “Gig Performer on Windows” forum, where they have been experiencing the same thing. I found that the tip suggested there to close and re-open after selecting a different rig worked for me also.