Q: 2-way syncing issue between Calendar app and Google

I am using Calendar 8.0 on OS X 10.11.6. I have several different calendars in my Google account synced to the Calendar app, and 2-way syncing was working fine. I could create an event in my browser in Google Calendar and it would appear in the Calendar app, and vice versa - I could create an event in the Calendar app for a specific calendar in my Google account, and that event would appear in my browser under the appropriate Google calendar.

Now, if I create an event for one of my Google calendars in the Calendar app, it does not appear in the browser. I'm not sure what, if anything, recently changed. Events I create in my browser still appear in the Calendar app, and the really bizarre thing is that I can delete an event from one of my Google calendars in the Calendar app, and it gets deleted in the browser as well. But if I create an event in the Calendar app, it never gets pushed to Google.