My computer's Calendar.app displays two calendars: mine (DB) and my wife's (MM), shared via iCloud; both computers run High Sierra. The sharing works just fine.
But now there's a number appearing next to her calendar's name:
What's the meaning of this number "1"? And now that it's a day or two later, the number has increased to "12." I could imagine it represents new entries in her calendar, but then it should go away when I look at it...and it doesn't.