Why don’t deleted or rescheduled events sync to iCloud Calendar?

Hello Folks,

New Event created by the assistant with outlook client is replicated to the CEO iphone's calendar. Normal ....

If the assitant with a shared access to the calendar reschedule or delete the event with the outlook client Office365, the event often remains on the Iphone (at first scheduled date if date and time has been changed or evenhas been deleted) It is not always the case, I cannot reproduce the problem when I test, but it happen often. Of course it is a CEO calendar so it is full of events every day.

Any ideas where the problem reside ? I update IOS to last version 18.5. Exchange servers are to the latest version and the outlook client is office365 running on windows11.

I don't have the problem on Ipads.

Thanks for your help.

[Re-Titled by Moderator]