Thanks for looking at this for me. Your suggestion returns the record when the event date is one month from today, but it doesn't work if the DateAdded is within one month of the EventDate. It seems to be the second where clause that doesn't work:
(calendar.DateAdded = CURDATE() AND calendar.EventDate BETWEEN CURDATE() AND DATE_ADD(calendar.EventDate, INTERVAL 1 MONTH))
So if I have an event on 2022-01-07 and I add it today, I want it to return the record but the above query doesn't. Not sure if it's relevant but EventDate is a Date field and DateAdded is a Timestamp.