Fenix 6x Solar Pro Temperature and Altitude not working , even after perform a hard reset

Hello 6744771

I am sorry to hear you are having this issue. For this, there are a few initial recommended troubleshooting steps to try. Troubleshooting the fēnix 6 Series Altimeter and Barometer : 

• Ensure you are calibrating the altimeter regularly, in particularly before starting the activity. 
• We also recommend cleaning the altimeter sensor port. This is found on the Right side of the watch, between the buttons: 
  1. Run low pressure, warm water over the sensor port.
  2. Gently remove any visible debris.
  3. Shake away excess water and allow to air dry.
  4. Calibrate the altimeter.
• If this continues, we would recommend trying a full factory reset with these steps: 

If this issue continues, you can contact Garmin here: Garmin Product Support