I think I have found the reason.. notifications for click had been turned off.. new one on me... I've set it for later today.. I will wait in anticipationPixel 6 pro running Android 14.
This last week I have set 2 specific "morning" alarms.. checked before going to bed.. both alarms failed to go off and appeared as if not set when checked in the morning.. only started happening in the last week .
The clock notifications setting seems to have fixed it.. I hadn't knowingly switched notifications off.. very oddIf that doesn't work, then also look closely at what days of the week the alarm is set for. If none of the days are highlighted, then the alarm is for every day. If at least one of the days is highlighted, then it will only go off on those particular days of the week.