Not holding compass calibration

I am having some problems with Cube Black, PX4 and Here3 RTK. On boot up sometimes there is no GPS detected, also occasionally I find the system asking for compass calibration even once it’s been successfully done. After sitting idle and in standby I find that occasionally will switch to and from ready and bad AHRS. Drone will fly fine once settled (which could involve a few reboots).

Does anyone have any pointers on what this could be?

Thanks

Mat

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