Do It is a big help.
By the way, this business of swapping out the Elements of a List Picker in the AfterSelected event is very awkward, like asking the List Picker to hop with its pants down.
It's more natural to arrange a hierarchy of List Pickers in a row, horizontal or vertical, like bread crumbs, to progress from major to minor selection, showing their Selection values in their .Text values, like bread crumbs. The Selected List Picker uses its Selection to load the next lower List Picker's Elements. For example, think of (Country, State, City) List Pickers. That also eliminates the business of swapping out Elements while open.
The BeforePicking event is a safer place to load the Elements of a Picker.
Here is a sample app to study that reloads a List Picker on the fly.