Catalina calendar app issues - Birthdays calendar is not working properly.

[Eurus]

I have a problem with stock calendar app. "Show birthdays calendar" option uncheck itself every time I close the app. I turn on the option, and next time I open calendar app it is turned off. Is there any way to solve this? I use Catalina 10.15.3. iOS calendar app is working properly.

 

[Ritsuka]

Try to remove the Calendar app preferences.
Close Calendar, open Terminal, paste

defaults remove com.apple.iCal

and press enter.

 

[Eurus]

Try to remove the Calendar app preferences.
Close Calendar, open Terminal, paste

defaults remove com.apple.iCal

and press enter.

Unfortunately, that didn't solve the problem. I reported the issue to the Apple, but so far nothing has changed, even though I reported it in the first version of the Catalina.