[SOLVED] Cannot create new NavigationBarItem since 2.0.13

Attempting to create a new NavigationBarItem (i.e var navitem = new NavigationBarItem()) in 2.0.13 causes an exception:

Object reference not set to an instance of an object

at Wisej.Web.Ext.NavigationBar.NavigationBarItem.Update()
at Wisej.Web.Control.set_TabStop(Boolean value)
at Wisej.Web.Panel.set_TabStop(Boolean value)
at Wisej.Web.Panel..ctor()
at Wisej.Web.Ext.NavigationBar.NavigationBarItem..ctor()

Best I can tell this is not due to any change in the navigation bar but may be due to a change in the items collection of the underlying Wisej.Web.FlexLayoutPanel? It was working fine in the previous version.

TIA

Nic