Flashlight feature gets stumbled with the "Gesture" backlight setting (I have it set as "After Sunset", but it also fails if you set it "On")
What occurs is that the flashlight gets off depending on your whist position (because of gesture detection), so if you try to face watch towards the floor (something normal as you are trying to use the flashlight to see the floor during night)
Fenix 5 fw 6.0.0
