iCloud calendar is read-only in Microsoft Outlook

On a PC running Windows 11, I installed the "iCloud for Windows" app from the Microsoft store and told it that I want to sync calendars and contacts with Outlook.

Outlook now lets me create and delete calendar entries, and change their titles, but it will not allow me to set or change the time or date of a calendar entry. When I try to change the time, it immediately snaps back to 8 AM.

I think this is a recent behavior change. Any idea where to look for the problem?

I have, of course, tried completely removing and reinstalling iCloud for Windows.