Hi,
it seems that after resuming an activity the varia radar is no longer detected by the watch and thus becomes just an expensive rear light for the second part of the trip.
I've experienced this twice during long cycling activities when you pause / suspend the activity and resume it later.
When the activity starts, the radar is working as designed but after a long suspension (either using the stop button only one, and then choosing resume a few minutes later or by choosing resume later (I assume from the French labels on my watch) and restarting the activity.
First time I also switched off the radar during the pause, second time I did not but I might have become of range a few minutes.
I am using a Fenix 5 on v8.0.0 and Varia Radar with also lasted firmware (3.8 IIRC)
Thanks for your help
Jérôme