Steps to reproduce:
radScheduler.ActiveViewType = SchedulerViewType.Timeline;
radScheduler.GetTimelineView().ShowTimescale(Timescales.Hours);
radScheduler.GetTimelineView().GetTimescale(Timescales.Hours).DisplayedCellsCount = 10;//set 8 for workarround.
radScheduler.ActiveView.StartDate = DateTime.Today;
radScheduler.GetTimelineView().RangeStartDate = DateTime.Today.AddHours(7);
radScheduler.GetTimelineView().RangeEndDate = DateTime.Today.AddDays(1);
radScheduler.GetTimelineView().ResourcesPerView = 5;
radScheduler.GroupType = GroupType.Resource;
radScheduler.SchedulerElement.SetResourceHeaderAngleTransform(SchedulerViewType.Timeline, 0);