EKF/Compass Error only during yaw "left" command

Hello Everybody,

I’m using the Pixhawk2.1 with Here+ GPS. In Compass Config, the internal compass is disabled.

Flight performance is very good but when I send a Yaw command to turn left, I get terrible compass values and the EKF Compass Bars are red. If I turn “right” on yaw, nothing happens.

I have no idea why this happens! Yaw right, no problem! Yaw left, EKF Compass Error and fully red compass chart in EKF HUD.

Firmware is 3.5.0 -rc11, X-frame, OctoQuad.

Thanks for your ideas and help.