I'm having the same issue in FS2024, when I turn off AP-1 the speed brakes on the right side will retract. When I then engage AP-2 instead of AP-1, they remain retracted, as they should. If I engage AP-1 again, they extend again.
Edit: After 15 minutes or so flying with AP-2 the autopilot seems to be slowly but surely extending the right speed brakes anyway.