The iCloud calendars in my iOS Calendar app do not sync manually (for at lest a couple years now). In order to get them to sync, I need to trigger a manual sync by selecting the list of calendars in the iOS app, and dragging down and releasing. This reliably works to trigger a sync, but I see no setting in the app to sync automatically. Sometimes changing or adding an appointment in the iOS app will also trigger a sync, but not always.
Is there a way to get iCloud calendars to sync automatically with the iOS Calendar app?
I have tried rebooting all devices. Logging off iCloud and logging back in, and restoring and rebuilding the installation on my iOS device. Nothing helps.