Edge 840 Solar sleep mode does not activated by power button

Dear Community,

I’ve started using my new Garmin Edge 840 Solar 2 days ago and everything was fine until now.

All of a sudden, a short press on the power button doesn’t trigger the sleep mode. I can hear a beep but nothing happens, I keep seeing the chosen activity profile on the screen.

The strange thing is that long pressing the button works, I can choose Power Off, Sleep Mode, etc., but short press does nothing. It worked before.

Any tips?

Thanks!