Fenix 8 43mm (os 11.90) keeps loosing connection with HRM-Dual

My Garmin keeps losing connection with Garmin HRM-Dual when I am not in training activity.

  1. I put on my HR strap on my chest.
  2. I take off my watch.
  3. I check that the sensor is paired and connected -> it is.
  4. HR is visible for a few seconds, then it is gone.
  5. I check that the sensor is paired and connected -> it is not...

It is working okay during activities, but not in that scenario.