With so many anecdotal stories of compass "kiss of death" problems, some amateur sleuthing might give a clearer understanding of it.
1 "Fly " your spark by hand all over your house and garden. See if you get yellow or red compass anywhere.
If you do, see how far you move before it goes. And whether it triggers error message.
2. Leave it on compass scereen and fly it around. Slowly approach say a metal gate and observe the compass. I've not found any interference so far.
When I get a chance I shall "fly" mine by hand under some power lines and the like to gauge it.
3 Never recalibrate until you have checked the compass screen and moved well away to see if  normalises. Otherwise you're calibrating the error in.
4. Perhaps a qualified person could explain how the addition of another compass solves this, since it is subject to the same local conditions. I accept it will, but I always like to understand.
5. Publish any interesting finds for us all. Thanks.

Very good advice, thank you for sharig it!