Hi mansing.tse,
Could you go to Clock's App info > App notifications, and show me your notifications settings?
Please check if your do not disturb setting accidentally blocks the clock.
Go to Mobile manager > Notifications, make sure "clock" is not blocked in notifications, to allow notification, please switch to "on".
In Mobile manager > Notifications > upper right corner three dots, check if there is an "unblock" option, if there is, please unblock Clock.
If the problem is still appearing, please tell me your firmware version.
Please also show me the screenshot of your confirmation message, and a short video of the problem if possible.
Thank you 🙂