After selection from ui select box, the selected option will not be attached (not displayed) as selected

I created a plunker for this: http://plnkr.co/edit/5nk4BnYoO52En7P6kPu9

Select a selection, but when you select one the ui-select will remain empty. Potentially important note: I am using this inside a (ui-bootstrap) directive. As a side note to this - there is no packing directive in the plunker, so this is not the culprit.

<ui-select search-enabled="true" ng-change="updateMedu()" style="width: 100%" ng-model="medications.chosenMedications.metadata.conceptGroup.conceptProperties">
    <ui-select-match placeholder="Please click to choose or start typing dosage value..">{{$item}}</ui-select-match>
    <ui-select-choices repeat="cp in medications.chosenMedications.metadata[key].conceptGroup[1].conceptProperties | filter: $select.search">
        {{cp.synonym}}
    </ui-select-choices>
</ui-select>

      

        
        
        
      

    

Manual dataset layout:

$scope.medications.chosenMedications.metadata = [
    {
        conceptGroup: [
            {
                conceptProperties: [
                   {synonym: "Item One"},
                   {synonym: "Item Two"},
                   {synonym: "Item Three"}
                ]
            },
            {
                conceptProperties: [
                    {synonym: "Item A"},
                    {synonym: "Item B"},
                    {synonym: "Item C"}
                ]
            }
         ]
     }
];