Compass Debate

If there is electro/magnetic interference, the compass might warn you.
But recalibrating the compass won’t do a thing to correct the problem that the compass is warning you about.
In that situation, the only solution is to power off, move away from the problem and start again.

I was pointing out that just because it worked last week doesn’t mean it’s going to work every time. Something as small as being too close to metal at certain times can trip it and a reboot doesn’t always fix it so sometimes it does take a recalibration. I have been on sites in the middle of a field that threw compass errors even though there was absolutely nothing visible that should have tripped it so it very easily could have been that there was something underground. I had to go about a quarter mile away to take off and fly back to the site. This was back before we had this new warning. That said if it is doing it almost every time then there is either something wrong with the software causing a false positive or the drone itself. I am guessing most likely the software since this is a new function.

If you properly understand what compass calibration actually does, you understand that it cannot “fix” a problem in your local environment.
Compass calibration is only about the magnetic fields that are part of the drone itself and shouldn’t be required unless the drone is modified or crashed.
I’ve been working a P4 pro hard for over four years and never calibrated anything on it.
It worked perfectly last week, it worked perfectly 4 years ago and for >1000 flights in between.

Of course a compass calibration is not going to fix the interference, but if you understand what a magnetic field is doing and how a compass works you would know that it fluctuates and all it takes is for the compass to be disturbed for the system to throw a fault. I can only speak to what we have experienced over the last 6 years and 2,000+ flights and how we have overcome those issues. If you can clear a software fault by doing a calibration then it is a remedy regardless of whether or not it actually did anything to the drone or compass. You should consider yourself luckily if you have flown that much without ever experiencing a compass fault.

I suspect you are misunderstanding the compass and how it works.
The term compass error is misleading and gives the impression that there is a problem with the compass that needs to be fixed.
It would be better thought of as a compass warning and what needs fixing is your location relative to the source of the problem.
My “good luck” is entirely down to properly understanding how the compass actually works.