Hi My fenix 6x heart rate sensor shows rate and work even when I don't use my watch !!!!! How is it possible?! What should I do?

Is it the same even if you put the watch with the face down? Do you see the green lights flashing?

The first things you always should do when you run into problems is to:

1. Restart your watch by holding the light button for ~15 seconds.
2. Connect to Garmin Express and install any updates.