When an on-market listing has in-person showings already scheduled and a digital access device is added to the listing, all showings that haven't been confirmed by the prospect will change to self-show so that access codes are distributed based on your current configuration. All communications required to complete the self-showing will be sent automatically. All showings that have already been confirmed will remain in-person showings. 

Similarly, if a self-showing has already been scheduled and a lockbox is later removed prior to the appointment time, all unconfirmed showings will be switched to in-person showings. All previously confirmed showings will complete as self-showings. 

If this behavior doesn't meet the needs of your agents or the prospect, your team can Re-Schedule the Showing to ensure that the preferred showing method is utilized.