I have a List view where children are generated dynamically from a variable that is a List of data type (it has the field type which can be either produkt or bundle). From this list view I can add the indiviual items to an app state of the type: List<Data Type, int> (Data Type is the List item and int =1). Although this seems to work as the values are possible to map individually and in the debug panel the app variable looks as expected the list view suddenly shows a null error when it holds items of the type produkt. What confuses me is that this used to work very well a few hours ago and it didn't make any changes in that logic since. (Basically it's the logic from the marketplace item E-commerce sample application, just customized a bit).