Bug? GPS lost during activity

Did two rides now with Fenix 7x Sapphire. First ride 118km, no issues.

Second ride 52km. After 45km I was on a deserted road, no traffic and started to tinker around in the menus, viewing solar activity etc. On returning to the activity, GPS was lost. Didn't get a fix again on wide open area. Even stopped for 2 minuts, no fix.

Stopped and saved the activity, started a new one. Instant GPS fix.

Seems like  a bug, anyone more info?