Hi Dave Branson,
I am sorry for the delayed reply,
It seems that the UI thread is busy while the processing works. Have you tried putting the blocking activity in a Dispatcher? This way hopefully the UI will have time to update:
ShowStatus("Formatting Data for " + ti.Header.ToString());
this.Dispatcher.BeginInvoke( () => ProcessActivityTab(ti) );
Does this work in your case?
the Telerik team