A XamPropertyGrid exists in a view and is bound to a Model property in a ViewModel.  The Model property is a reference to an object A which contains two Properties that are data retrieved async from a server.  The first property is data for a collection.  The collection is instantiated before the screen is gathered before the screen is displayed.  the data for the collection is retrieved early.  The second property is a class with several subclasses.  it's instantiated early as well and filled with data just after the first property is populated.

The property grid does not display the data for the first property in the grid(the collection) but it has a placeholder for this property in the property grid,

The second property is displayed in the property grid. 

I've done everything I can to get the first property displayed in the grid.  Why is it so sensitive?  is it a timing issue?  How can I force the property grid to reload all the data?

the property grid exists in a tab.  if I switch tabs and return to that tab the data gets displayed.