Calendar notifications stopped working

I rely on my calendar notifications to alert me of upcoming events and meetings, usually setting 2 reminders. I've noticed this week however that I am not getting any notifications at all, on either the mac or iphone. Notifications for calendar are turned on for both, and I'm even testing it by setting alerts for new appointments a few minutes in advance, and despite the appointments syncing between devices, no notifications come through on either. Focus mode isn't enabled.

can anyone help me get the alterts working again? They have worked fine for years. and now they don't, I get nothing at all. I'm having to use Google calendar instead in the short term as I absolutely rely on appointment reminders.

TIA