I too have issue with DCM Roll/Pitch inconsistency as well as bad AHRS health on Matek H743 Wing. I’m running on EKF3, I disabled all compass (they would generate errors all the time no matter how well they where calibrated) and I encounter this while having a solid GPS fix (13+ satellites). (Arduplane 4.0.9)
I do believe this could be partially related to cold weather causing issues with compass and IMU, but could be a coincidence as well.
Due to a issue in DCM related to compass fusion for yaw when pointing straight up, sometimes the AHRS subsystems will disagree when powering up, nose up. Slight errors in compass calibration, while resulting in a successful calibration, may worsen this effect.
The result is that some setups will give a pre-arm failure. Typically it is “Pre-Arm: DCM roll / pitch inconsistent by” x “degrees” or similar. If this happens consistently, then one of two solutions can be used:
Power up horizontally, and allow the autopilot to begin initialization in this position. After the IMUs tilt initialization is completed (usually in the first ten to fifteen seconds or so), the Tailsitter can be set vertically for the remainder of the initialization (ie after GPS lock and EKF is using the GPS) and then armed.
Or, if you get the Pre-Arm failure above, lay the Tailsitter down horizontally for 10-30 seconds to allow the various AHRS subsystems to synchronize. After that it can be raised and arming should proceed normally.