Calendar has repeated invitation appearing daily until 2026

I sent an invitation to a three-day event to my husband. It was declined. However, it immediately appeared daily in his calendar until Oct. 3, 2026, with the time being declined on each event. There's no option to delete the event, although each individual event gives the option to "cut, copy or paste", if "cut" is chosen event remains. I've compared our calendar settings on our iphones and they are the same, however, his contact card did not match mine as his nickname had been changed since I'd received his contact card so he changed it back to match mine. After that, the question mark next to his name in my contact card for him changed to a green check mark. I've deleted the original invitation and calendar event from my calendar, but his remains. He does not have an Outlook or Google calendar so there's no conflict there. I invite him to many events and this has never happened before or since. How can these unwanted repeating events be removed?