Multi-Select, doesn't call datafactory given a sequence of operations

I have an issue with moving between .SelectedObject and .SelectedObjects and seeing the proper calls to the DataFactory.  I use a custom data factory.  

.SelectedObject = "ObjectA"  (updates propertyGrid, ok)

.SelectedObjects = "ObjectA,ObjectB" (updates propertyGrid, ok)

.SelectedObject = "ObjectA" (no call to DataFactory, propertyGrid still thinks its multiple selected, note same object that started sequence)

========== new sequence ====

.SelectedObject = "ObjectA"  (updates propertyGrid, ok)

.SelectedObjects = "ObjectA,ObjectB" (updates propertyGrid, ok)

.SelectedObject = "ObjectB" (works, updates propertyGrid, back to single selection)

=========

In the first case, we've put in a call to set .SelectedObject=null prior to assignment of ObjectA, but it does cause an ugly flicker as the propertyGrid blanks out.

Thanks for any help.

jeff

Version 11.2.554.0