OnPropertyChanged(nameof(Thicknesses))ItemsSource="{Binding Thicknesses, UpdateSourceTrigger=PropertyChanged}"Thicknesses is supposed to be refreshed by 2 things :Material which each one contains a list of thicknessesOnPropertyChanged(nameof(Thicknesses)) is well triggered when one of the 2 case i mentioned is filled but the update seem to works only if change the Material but not when i add a new thickness to it.