The issue was that the code called a function that doesn't check for the active keyingset in combination with autokeying. The fix is to just call `autokeyframe_pose_channel` which does that check. I snuck in a minor change to the operator label. It spells out "Quaternions" now instead of shortening to "Quats". I haven't seen that way to shorten it in Blender before. Pull Request: https://projects.blender.org/blender/blender/pulls/122170