angular ng-options does not render the right value in IE 11

I have two dropdowns with ng-options. One for displaying primary brokers and other for secondary brokers. The Mark-up is as follows:-

<div class="col-md-4">
    <div class="form-group">
        <label>Primary Broker: </label>
        <button type="button" class="btn-help" tabindex="-1" data-popover="" data-content="Lead JLL broker for the opportunity">
            <span class="circle-help">?</span>
        </button>
        <select class="form-control"
                ng-options="jllContact.JllUserId as jllContact.Name for jllContact in controller.primaryJllBrokers"
                ng-model="controller.primaryJllContactId"
                id="primaryJllContact" data-field='{"name": "Primary Broker", "attribute": "PrimaryJllContact"}'
                ng-change="controller.setPrimaryJllContact()"
                ng-class="{'req': controller.data.isFieldRequired('PrimaryJllContact'), 'has-error': controller.data.isFieldValid('PrimaryJllContact') == false}"
                ng-disabled="!controller.isEnabled('JllContacts')||!controller.canEditBrokerAllocation()">
            <option value="">Select Primary Broker</option>
        </select>
    </div>
</div>
@* Secondary Broker*@
<div class="col-md-4">
    <div class="form-group">
        <label>Secondary Broker: </label>
        <button type="button" class="btn-help" tabindex="-1" data-popover="" data-content="Secondary JLL broker for the opportunity">
            <span class="circle-help">?</span>
        </button>
        <select class="form-control"
                ng-options="jllContact.JllUserId as jllContact.Name for jllContact in controller.secondaryJllBrokers"
                ng-model="controller.data.SecondaryJllContactId"
                id="secondaryJllContact" data-field='{"name": "Secondary Broker", "attribute": "SecondaryJllContact"}'
                ng-change="controller.handleSecondaryJllContactChange()"
                ng-class="{'req': controller.data.isFieldRequired('SecondaryJllContact'), 'has-error': controller.data.isFieldValid('SecondaryJllContact') == false}"
                ng-disabled="!controller.isEnabled('JllContacts')||!controller.canEditBrokerAllocation()">
        <option value="">Select Secondary Broker</option>
    </select>
</div>

When I change the secondary broker, as seen in the markup I call a method called handleSecondaryJllContactChange. The method is as follows.

handleSecondaryJllContactChange:()=>
    primaryJllContactId = this.primaryJllContactId
    this.refreshPrimaryBrokers((primaryBrokers)=> this.primaryJllContactId = primaryJllContactId)

  refreshPrimaryBrokers:(callback)->
    this.primaryJllBrokers = _.where(this.data.JllContacts, (jllc)=> jllc.Role.ID == 21 && jllc.JllUserId != this.data.SecondaryJllContactId)
    if callback? && callback!= undefined && this.primaryJllBrokers!=null && this.primaryJllBrokers != undefined
      callback(this.primaryJllBrokers)

As seen from the code, we are setting the ng-model "controller.primaryJllContactId" for the first drop down after the collection controller.primaryJllBrokers has been refreshed.

However, the drop down still shows instead of the correct option in IE 11.

NOTE:

1. On examining the console, we did notice that ng-model for the first dropdown controller.primaryJllContactId has the right value. It just doesn't display correctly in the drop down.
2. This is happenning only in IE 11. It works perfectly in chrome.

Couple of things we have tried:-

1. Instead of ng-change="controller.handleSecondaryJllContactChange()" in the second dropdown we tried to have a watch on controller.secondaryJllBrokers and call the method controller.handleSecondaryJllContactChange().
2. The second route which we took was based on the assumption that we are setting the ng-model before options are rendered. Hence we took the $timeout approach. In the handleSecondaryJllContactChange() method shown above we did this in the second line:-

this.refreshPrimaryBrokers((primaryBrokers)=> this.$timeout(=> this.primaryJllContactId = primaryJllContactId))

None of these two approaches worked. Any ideas why this is happening and what is the way to know when options have finished rendering.

Thanks in Advance !!!!