I'm getting this with UI for WPF R3 2016. It was not a problem with an earlier version (Q1 2016). A workaround I found is to implement a DataFormCommandProvider and override the AddNew method. There I added a "dummy" item to the ItemsSource collection before calling base.AddNew(), and then removing it again afterwards. I don't like this workaround very much, so a proper fix would be nice