Hi Laurence,
Thank you for contacting Syncfusion support.
Based on the shared information we have analyzed your requirement Appointment need to be visible while Appointment and NonAccesibleBlock added on the same TimeSlot. As per Schedule implementation, NonAccessibleBlock is the upper layer of Schedule, hence appointment on the same slot will be overridden by the NonAccessibleBlock and it’s the expected behavior based on the implementation.
Kindly revert us if you have any concern.
Regards,
Farjana Parveen A