I believe the issue stems from the recent iOS 17 update, particularly due to changes in privacy and security settings concerning third-party app access. Sometimes, after an update, permissions might not function as expected.

To address this, you can manually grant access. Here's how:

1. Open the Apple Settings app.
2. Navigate to Privacy & Security > Calendars.
3. Ensure "Full Access" is granted to the app.

I hope this helps!