Some of the Google Clock users (including me) was facing the issue with the alarm features. I am sharing my experience here.
Just after updating my phone to OREO, Suddenly my morning alarm doesn't go off anymore and I was late for work for 3 days running.
Since the last update, the clock app has been dismissing the alarms as soon as they start to go off. I have noticed if a set an alarm a minute from now it works. When I set an alarm for tomorrow morning it dismisses itself.
This is what faced and I also found many more users also facing the same issue, after updating their phones to OREO.
Here is the link of the dicussion where other users also facing the same issue.
Here we have the fix of this issue, Thanks to the AndroidPolice guys, They shared the bug fix update on APKMIrror.
Go through the below link to download the APK File