I set an alarm for 8:55am and it never went off. At 8:58 it was saying that its 38mins until its due to go off.
Ice also had one time alarms just never set, and some issue with the stopwatch.
Alarms are important to me.
What app do you use?
Someone can softfork them, change the App IDs to org.lineageos.x and release apks.
I started doing that a while back, but Android dev is complicated.