Taken from my comments inside the code
The following code will not work here (Inside loadSaved() in the Controller class at line 415) as I believe adminListView is null since the screen that has it in it has not come up yet. If I put it in the startLoaded method it seems to still act the same. If I put it in a method called when a button on that screen is hit it will run without any errors but will not add the correct items.
for (int i=0; i<admins.size(); i++){
adminListView.getItems().addAll(admins.get(i));
}