there are problem with coloring Cell. You are colorig them by BackColor or NonBussinessbackColor. Problem is there after export some weeks start for example on monday, another in saturday. Then if cellduration is 10080 one weeks have backColor, other NonBussniessBack Color.
I suppose there is problem in: isBusinessCell(DateTime) in DayPilotScheduler.cs. Add condition on start:
if (CellDuration > 1440)