I just updated to Android 9, and was no longer receiving message text notifications or email notifications - either on ambient display or on the 'notifications bar'. All notification settings were turned on. Called Google support, but (surprise!) they were of no help - with the rep even saying that those notifications should not show since her phone also did not show those notifications!! After trying everything, I realized that in Settings/Sound/Do Not Disturb, the phone had been set after the update to turn Do Not Disturb 'on'. Turning it off solved the problem. Curious whether anyone else had this problem.