Your interlocutor has told you or Julie that he has not received the invitations that was sent to him? But he appears on the event’s list of participants? If you are using an iCloud calendar account, two reasons could explain why your contact has not received the invitation:
The email address your contact uses to receive the invitation is linked to his iCloud account
The account to which the invitation was sent is the same address your interlocutor uses for his iCloud account. It would be the same address he uses to connect to the AppStore.
If this is the case, he does not receive the invitation because his iCloud calendar retrieves the invitation directly, without it even going through his email inbox. In this case, your contact must modify his iCloud account configuration, as explained here .
Your contact’s email address is hosted by Office365
If your contact uses an Office365 email account and calendar, which may be the case for many professionals, he will not see the invitation appear in his Office365 calendar because .ics files originating from iCloud cannot be opened by Outlook.
The solution is to download the .ics invitation file attached to the invitation email and open it with a third party calendar application.
We understand that this might not be the easiest or most transparent way for your contact to handle an invitation but unfortunately, this is a iCloud or Outlook limitation that we cannot ignore.