strangeness with calendar on mac

Hi all,
As of today, something very frustrating has started happening with my calendar.
I always have my mac calendar view set to month view. This is the view I prefer, so I can see my work schedule out weeks at a time with minimum hassle. However, when I go to the day I want to look at, tomorrow for example, and interact with it, voiceover says content is empty. I know there are events there, because they show up on my phone. Voiceover also sees them if I set my calendar view to week view. The suddenness of this all is the most perplexing thing to me. It was working fine yesterday, but now it doesn't. I'm running Mac OS El Capitan version 10.11.6, if that matters.
Any help with this would be greatly appreciated.
Cheers,
John