Unfortunately, I was not able to reproduce this issue. The following code is working for me.
var list:PickerList = new PickerList();
list.dataProvider = new ArrayCollection([
list.popUpContentManager = new DropDownPopUpContentManager();
Are you using a custom item renderer? Which
IPopUpContentManager implementations did you try?
Note that if you use
Event.CHANGE won't be dispatched until the pop-up closes.