Yesterday, my MODX7 (OS v2.52) detuned itself by about 30 cents. I've tried initialising all settings to no avail. As a temporary fix I've adjusted the master tuning to 448Hz but I can't believe there's no onboard calibration for such an essential function.
You're quite right. The pitch wheel is continuously sending data. I don't understand why that's affecting the master tuning though.