Broken in version R3 2016 (2016.3.913)
How to reproduce:
SchedulerDayViewElement dayViewElement = (SchedulerDayViewElement)this.radScheduler1.ViewElement;
dayViewElement.SetColumnWidth(1, 2);
Workaround:
IDictionary cachedSum = (IDictionary)dayViewElement.GetType().GetField("cachedSum", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(dayViewElement);
cachedSum.Clear();
IDictionary cachedColumnHorizontalOffset = (IDictionary)dayViewElement.GetType().GetField("cachedColumnHorizontalOffset", BindingFlags.Instance | BindingFlags.NonPublic).GetValue(dayViewElement);
cachedColumnHorizontalOffset.Clear();
SchedulerDayViewElement dayViewElement = (SchedulerDayViewElement)this.radScheduler1.ViewElement;
dayViewElement.SetColumnWidth(1, 2);