Apple Notes Synchronisation Error with iOS26

• Issue

The well-known fast synchronisation of Notes via iCloud does not work.

• Scenario

Regular operation; both devices updated. While the Notes app on the Mac shows no particular exceptional loading activity, the iOS app behaves strangely. The loading wheel in Apple Notes on iOS26 spins continuously while no notes are synchronised to and from the iPhone. The existing notes are on both devices, but anything newly created is not synchronised.

• Actions taken

Everything known, in sequence: Internet Access on both devices, Restarted apps, Restarted Devices, Reinstalled Apple Notes on iPhone, furthermore on iPhone: Deactivated /Reactivated iCloud, Removed Apple ID, reactivated Apple ID, Re-enabled iCloud sync for Notes

• Result

It worked -but only yesterday.

This morning, the same problem occurred again. The loading wheel in Apple Notes on iOS is endless, although, as mentioned above, the basic set of notes already exists. It's just the latest notes that aren't synchronising). Every time I open the app, I see the loading wheel icon for a long time. But nothing happens.

• Question(s)
  • Since this is my last resort before (once more) contacting Apple Support, is anyone else experiencing the same issue with iOS26 and synchronisation of Notes with iCloud?
  • What helped to permanently resolve the issue?

• Note: 
  • I am intentionally asking the above questions and obviously ask not for just any knowledgebase articles that contain random steps for a possible hope -which I tried out already. Thank you for your understanding.
  • It is with an iPhone 13 mini, NOT an iPhone 8. I did not select iPhone 8 here and cannot change it either.