Compass inconsistent in Sheltered area

Anyone experience this. I tried to fly my drone in an sheltered area using althold. The gps isn’t getting a fixed but definitely receiving some satellite feedback. So its giving a gibberish position. Thats fine because I am flying in altihold.
But then the compass seems to give problems as well which seems to affect the direction of the drone. And errors like inconsident compass variance start popping up after like 10 mins flight.
Is there a bug? Or its my accel problem? When I put my drone in the open with a gps fixed every goes back to normal.
Anyone experience compass problems when you are having some satellite but no gps fixed (after prolong flight in this conditions)?

You are probably getting interference/shielding from the sheltered area you are in. Compasses are not super reliable indoors.

Perhaps so. Just wonder do the compass took any reference from GPS data could the compass be taking the wrong reference from the gibberish position after prolong flight. I actually had the problem at second battery flight.

Does accel get affected if GPS antenna is too near?

I don’t know exactly when this happens - but it does use GPS to get the magnetic field of the Earth at your location to calculate compass offsets. So if the gibberish is getting points way far away - the offsets may be updating incorrectly as well.

Accelerometer is not effected by GPS antenna.