Hello, my Apple Mail notifications have been working for years without a hiccup, but about a month ago I've stopped receiving notifications in the right upper corner of the screen. Also, no sound for new mail, all I get now is a number of new messages in the dock. When it started I was using Mojave so I thought that upgrading to Catalina will solve the issue, but no such luck. I've tried multiple solutions from around the web – turning sound notifications on and off in Apple Mail preferences, turning notifications on and off in the Notifications Centre, shutting Notifications Centre off from Activity Monitor, then rebooting. The weird thing is, they started to work normally again for about a day, and then they stopped again. Though not the biggest problem in the world, it's really messing with my workflow and I've grown accustomed to these notifications over the years, and it's really irritating. I'd really appreciate the help.