I was working on recently development task related to ICal files (.ics) generation. I used for testing native Windows 11 Calendar Application. On starting the application was not set up on my computer. Clicking on file opened the Calendar app using the system’s default association. Initial setup went smoothly, but on second time Calendar did open correctly and froze showing only empy screen. This situation repeated on any new attempt.
After some searching and testing I found solution what worked in my case. Open Settings, select Apps and from there Installed Apps:
Search for calendar application and open Advanced Options:
Verify that calendar is switched on.
Set background permission to Never and finally use Terminate button to ensure that program is closed.
At least for me, this solved the issue. Opening Calendar application with clicking on .ics file did not hang anymore.