EKF3 IMU0 Forced reset on latest dev 4.1.0 with Omnibus F4 Pro v3

Have been testing a custom version of latest Plane 4.1.0 code on an Omnibus F4 Pro v3 board for Alex (Yaapu) which contains some cool Terrain aware telemetry additions for the passthru protocol. I have been unable to arm the plane due to the warning message “EKF3 IMU0 Forced reset” which appears regularly after boot. I Tried the regular ‘Latest’ plane 4.1.0 dev version on this FC board also with the same results. I installed the current 4.0.9 Release version and this arms without issue. Link to log file below.

I found some posts suggesting to disable INS_FAST_SAMPLE=0, so tried this but no improvement. Not sure if anyone willing to take a look, but would be grateful if you can as I’d really like to get testing the telemetry changes. Thanks, Paul A

I have noticed that with Latest version described above that its no longer possible to switch back to EKF2. If you do that then on reboot, its back on EKF3. I regressed to the current release version 4.0.9 which defaults to EKF2 and that does not have the reported issue - arms and flies perfectly. Even switching that version to EKF3, the issue does not appear - but I do see compass variance errors doing that.

One strange observation - I tested this firmware revision on two planes and it only surfaces on one of them - the one which shows the issue is a regular plane (Volantex Ranger 2000) - with Ailerons, Elevator, Rudder and flaps - running on an Omnibus F4 Pro v3 board with Matek GPS/mag. The other which shows no issues is a flying wing (z84) with just two surfaces of course, and this runs on an Omnibus F4 Pro v2.1 with BN-880 GPS/mag. Both of these have the mag enabled, neither have an airspeed sensor.
Not sure if any of that helps. Cheers, Paul