Hello this is quite annoying issue. It does not happen always, but often enough.
I have my alarm set to wake me up in the morning, but sometimes it starts to ring but the screen is locked so I can't stop it! I have to unlock the screen but alarm is not on the screen, so I have to go through notifications and find it there! This is super inconvenient. If there were other people sleeping or I was in the meeting or whatever I would totally disturb everyone around before I manage to stop the alarm! Please check and fix this.
yes I am using default clock. About question In don't understand why you ask. I already wrote in OP that when this happens the screen is locked, so no I don't see any snooze.
Thanks, the reason I asked that is because normally even when the screen is locked, the option to Snooze comes up at the bottom. Try this: Settings > Apps > Clock > Storage > Clear cache and restart the phone.
If that doesn't help, can you confirm if you have Do you have Do not disturb mode on?