There seems to be some sort of weird lag on some notifications. The other day, I clicked to dismiss all, and nothing happened, so I thought I'd make a tea then look at the logs while I clicked. When I got back with my drink (call it 7 to 10 minutes) ...
I'm beginning to wonder if it's some misconfiguration from the Google server end. They do break things quite regularly. The past few reminders I've had have cleared without issue. Have you looked to see if it's showing anything in the Error Console?
