Fenix 5s plus compass not working - no calibration possible

Dear all,

I have significant problems with the compass of my Fenix 5s plus. It is not working correctly. When I hold it horizontal (like a compass is meant to be used) it is behaving crazy (always showing 20 to 50 degrees deviation from 0), but if I tilt the watch a bit to one side (bringing it out of level - I hope you understand what I mean) it jumps all across the bandwith from 0 to 360 degrees.
A calibration is not possible - always leads to an error / retry. (And yes, I know how to do it, works perfectly all the time on my 935).

Anyone else with this problem? Can I hope for a firmware fix? Do I have to send the watch back?