md-select works only once

I have this md-select :

<div ng-repeat="a in list">
......
<md-input-container class="md-block select-option-input" style="margin:0px" flex-gt-sm>  
        <md-select
        name="tableNo" placeholder="Nr. masa"
        ng-model="a.tableNo" ng-change="tableEdit(a)" class="md-block" flex-gt-sm>
            <md-optgroup  label="Nr. Masa" flex > <md-option
                ng-value="tableNo" ng-repeat="tableNo in getNumber(me.settings.tableNo)"  >{{tableNo}}</md-option>
            </md-optgroup> 
        </md-select>
</md-input-container>
....
</div>

which work only once. If I open the dropdown for the first time works good but if I try to open again it doesn’t open.

*on localhost works good.