When the timezone of the client is before UTC (e.g. UTC -1 or UTC -3) if you use the calendar for navigation, you will be navigated to the day before the selected one.
This doesn't work: apt.Description = DescriptionText.Text;
Thus, appointment resizing is not possible in RadScheduler with RenderMode="Mobile" if a time slot is tapped before tapping the appointment. Note: If the RadScheduler is scrolled between the time slot tap and the appointment tap, then resizing is possible again.