I have this same problem, but the explanation forgets one thing. Although the set up of the alarm may stay if you set it up on your phone via Garmin Connect, the alarm may be deselected due to an upgrade, so if you go to bed with the alarm set, the update will maintain the presence of the alarm, but deselect it so it doesn't go off....resulting in you being late for work, getting the sack, losing your house, and end up being homeless and addicted to alcohol.....not very fitness orientated is it Garmin?