RadzenDropDown order the selected item on top

I'm using RadzenDropDown in Multiple mode with a list objects as Data and bind to an IEnumerable<string>.
This works fine when.
When I want to modify my object the RadzenDropDown has the previously selected items selected, great!
But how do I show the selected items first?

I tried re-ordering the list, when opening the form:
List = List.OrderByDescending(x => SelectedItems.Contains(x.Code));
This does work, the previously selected items are now first in the list but they are no longer selected.

I must be missing something. Please advice.