To reproduce:
- Add complex controls to the backstage pages (add at least 4 pages).
- Change the pages at runtime.

Workaround:
Private Sub RadRibbonBarBackstageView1_BackstageViewOpening(sender As Object, e As System.ComponentModel.CancelEventArgs) Handles RadRibbonBarBackstageView1.BackstageViewOpening
    BackstageViewPage1.Visible = True
    BackstageViewPage2.Visible = True
    BackstageViewPage3.Visible = True
    BackstageViewPage4.Visible = True
End Sub