How can I get gmail notifications to start working on a Samsung Galaxy S10+?
I had the same problem with my new s10, and the clear data didn't work.
I had to dig in the settings to find it out that when turning the power save mode, it disables the auto syncronization.
You can manually turn sync back in the setting menu when you swipe down from the top. and preserve the power save mode.
Such easy thing but it left me several days without notifications.
Hopefully helps, and saves someone else's time.