AngularJS : ng-model binding not updating when changed with jQuery
Just use;
$('#selectedDueDate').val(dateText).trigger('input');
I have found that if you don't put the variable directly against the scope it updates more reliably.
Try using some "dateObj.selectedDate" and in the controller add the selectedDate to a dateObj object as so:
$scope.dateObj = {selectedDate: new Date()}
This worked for me.