I tried to set a defaulte value for this drop-down but this doesn't work how I expected and I don't understand why?

<select ng-change="onChange()" ng-model="selectedInfo">
        <option value="" selected>Default</option>
        <option ng-repeat="(index, info) in infos" value="{{index}}">{{info.name}}</option>
</select>

I need to have in value the index number beacuse is used in angular controller.

What I have now is

And at click I have

And after I select one of this I have just 3 options

How I can fix it?