Watch face goes back to default watch face.

I use the GearMin watch face for about four years. When I'm in Hiking activity and press the back button I see the default Garmin watch face. 

When I'm in Run or Trail Run activity and press the back button I see the GearMin watch face.

When I'm in hiking mode and press the menu button -> Watch face ->  the GearMin watch face is not in the list. 

I'm pretty sure that this was ok in the past. FW 26.00.

Any idea how I can fix this?

For testing purposes I've installed GearMin v3. Behaves the same.