When I try to link the rigs to another file, most of the controllers are greyed out, and don't highlight when I click on them. I can still use the rig, but the controllers aren't displaying the way they do if I just open the original file. I'm using Blender 2.83.1 on Windows, and I've enabled the included script.
UPDATE: Problem solved. When you link a character, it has to be [Robot name]_rig.001, not just [Robot name].