I have noticed this message occasionally appearing in the datalogs. Is it something to to be concerned with?
No, that is normal, and a good thing! Basically, when you are on the ground, the only directional reference is the compass. The EKF can provide an estimate based on fused data from a range of other sensors too, but requires some motion to do that. What you are seeing is just notification that this has happened.
I got same message and my hexacopter crashed.
Flight Controller: PIXHAWK PX4 2.4.7
Firmware version Copter 4.0.5
Transmitter: “FrSky Taranis Q X7 ACCESS 2.4GHz 24CH Mode2 Transmitter with R9M 2019”
ESC: Hobbywing XRotor 40A-OPTO ESC
Motors: Tarot 4108 High Power Brushless Motor (380kv)
Can anybody have look at log and help me what was wrong.