Appointments Vanishing from Fronted if Edited in the Backend

Shortocde [app_my_appointments] shows the list of appointments made. If any appointment is edited and saved in the backend by the service provider or admin, it vanishes away from the list in frontend, although it still is active and shows as such in the backend.

Plus the edited appointments now send two reminder emails simultaneously for the same appointment, both to the client as well as the service provider. They both receive the same email twice, at the same time.