AngularJS: ng-selected doesn’t show selected value [duplicate]

From the Docs:

Note: ngSelected does not interact with the select and ngModel directives, it only sets the selected attribute on the element. If you are using ngModel on the select, you should not use ngSelected on the options, as ngModel will set the select value and selected options.

— AngularJS ng-selected Directive API Reference

The ng-value directive is in the wrong place:

<md-input-container flex>
    <label>Anno selezione</label>
    <md-select name="annoSelect" ng-model="vm.anno_attuale"
               ̶n̶g̶-̶v̶a̶l̶u̶e̶=̶"̶v̶m̶.̶p̶r̶o̶g̶e̶t̶t̶o̶.̶p̶p̶r̶s̶[̶$̶i̶n̶d̶e̶x̶]̶.̶a̶n̶n̶o̶"̶                 
               ̶n̶g̶-̶s̶e̶l̶e̶c̶t̶e̶d̶=̶"̶i̶t̶e̶m̶.̶s̶e̶l̶e̶c̶t̶e̶d̶"̶ ̶  >
         <md-option ng-repeat="item in vm.progetto.pprs" 
                    ng-value="item.anno">
           ̶{̶{̶v̶m̶.̶p̶r̶o̶g̶e̶t̶t̶o̶.̶p̶p̶r̶s̶[̶$̶i̶n̶d̶e̶x̶]̶.̶a̶n̶n̶o̶}̶}̶
           {{item.anno}}
         </md-option>
    </md-select> 
</md-input-container>

For more information, see Using ngValue to bind the model to an array of objects