Enduro Alarms not working properly in Adventure Mode

Used Adventure Mode on my Enduro during a 100 hour race last week for the first time. Software 20.60

Set a Sleep Timer for 2 hours from now but it never went off. HOWEVER, as soon as you flick your wrist to look at the watch and turn display on then the alarm and vibration went off! 

Tried it also with repeating 10 minute alert and the same.

So, as long as you are awake and looking at your watch face then the alerts go off, otherwise they wait until you are awake! Is this a known bug as it makes the sleep timer pointless!!! ????

This happened exactly the same on 2 different enduro watches. Both in Adventure Mode. Mine was in a custom power mode based around full gps recording and the second watch was in UltraTrac. Both watches had screen timeout and had to flick the wrist up to turn screen on.