Why has Android blocked calendar notification

[Android Central Question]

I got s new phone OnePlus 7T. An transfer all my apps from old phone, Nexus. I very much depend on my Calendar notification. I tried to set it up but I keep getting this massage "at your request, Android is blocking this category of notifications from appearing on this device". I can't find anywhere how to change it.
Thanks for help.
IM

 

[SpookDroid]

Try long-pressing the Calendar app and tapping the INFO option (or you should be able to find that in the Apps section of your settings by looking up the Calendar app). There you should see a Notifications section; tap that. In there you'll see the types of notifications that are allowed/block for that app in particular.

Additionally makes sure you don't have a wearable device 'blocking' notifications on your phone to avoid duplicate displays. Same goes for 3rd party calendar apps.