Fenix 5s is no longer recording a GPS track while running.

Since sometime in late November my Fenix 5s is no longer recording a GPS track while running outdoors. GPS fix is there. Distance and pace are still shown.

I am using an HRM-pro together with the watch for running power. I added connectIQ data fields for that some time in autumn. There is something in the back of my head about using the sensors in the HRM-pro for distance and pace (via stride) instead of GPS... is there a setting for that?

Other than that, I am running out of ideas. I would assume that there still enough Fenix 5(s) users out there for a shirt storm if that would be a bug with a new firmware or something like that...

Any ideas?