Strange startup beeps and no EKF

Sometimes when I try to boot up my Pixhawk 4, I’ll get these startup sounds:

When this happens, the EKF doesn’t seem to start up and the vehicle won’t arm. It seems completely random as to whether or not it happens.

Any thoughts?

I think the issue may have been that the check for the internal compass in the rc.board_sensors was disabled. The check for the external compass was still enabled, but if ever it could not detect the external compass, the EKF initialisation would fail, causing this strange startup behaviour.