I am still experiencing this issue with 12.0.2. I keep getting the following error in the Thundebird console.
09:40:38.908 [calCachedCalendar] replay action failed: null, uri=Domain.com Remote Session - Domain.com, result=2147500037, operation=[xpconnect wrapped calIOperation] 1 calCachedCalendar.js:330:29
I’m trying to determine if there is anything else.
EDIT: I deleted my /home/user/.thunderbird directory and the calendar functionality is working without a problem.