false delete event messages on calendar

On occasion when a change to a calendar event is sent to me, the message received on my iMac is that the person originating the event wanted to delete the event. The same change is sent to my iPhone as either a change or added event, not as a request to delete.

If I accept the change/added event on my iPhone the delete message on my iMac disappears. Note, the originator of the event did not delete the event.