Troubleshooting Tips for Motors in QGC Vehicle Setup

I am wondering if anyone has a simple troubleshooting tip for why my motors seem to spin fine when I upload a flight plan from QGC or control them with the controller, but when I try to spin them in QGC Vehicle Setup, I get an error tone from the Pixhawk 2.4.8 and no movement on the motors.

All else seems to work fine - telemetry and/or direct USB, the Taranis XD9 plus controller, ESC calibration, everything else.