If two non-overlapping appointments are created in the same slot in multi-schedule view, both with durations less than the slot duration, one will hide the other.
1. select a 15 minute schedule
2. enter appointment A, starting at 9:00 and going to 9:05
3. enter appointment B, starting at 9:05 and going to 9:15
The 9:00 appointment will hide the 9:05 appointment.
To prevent this, appointments should be restricted to have start and end times on slot boundaries