Alarm not reliable - has days where it does not go off.

Well, as it doesn’t affect most users (if it did there would be an overwhelming number of posts about it), it must be something unique to your device. I have seen reports where this can happen if you have alarms too close together, so that the “snooze” time of one alarm overlaps another alarm. As an experiment, try deleting all alarms except the one that is critical to you.

As far as timing, engineering teams have thousands of issues to work on at any one time, and a fix for any problem has to be scheduled into a future release. They aren’t going to create a custom release just for you, and they probably won’t address it at all unless they have thousands of reports about it.