Calender Events - why is the original author the only user able to edit or delete?

Any other user gets an "Access denied" error when trying to edit the event. Even user 1, which has the highest level of privileges. This is happening on: Drupal 8.9.14 opigno_lms-8.x-2.20 opigno_calendar 8.x-1.7 opigno_calendar_event 8.x-1.4