Problem on iPhone 5 with input fields in a modal

Hi out there,
I’m continuing the discussion from Can’t edit the input fields [edit: Video]:
I have an issue with a input field in a modal. The modal contains a form with a input and with an select. I can gain the focus on both of them.

The keyboard is shown when I click on the input field (so it gains the focus). But typing is not working, so the text is not filled into the field. This issue only occurs on a iPhone 5 (iOS 7.1 or 8.1). It is working for Android and iPhone 4s & 4 devices.

If the same code is put on a default screen, everything works like expected (default ion-content). Has anyone any idea how to fix it?
I attached some code below.

###My modal code looks like this:

<div class="modal">
    <ion-header-bar class="bar-balanced">
        <h1 class="title">Login</h1>
    </ion-header-bar>
    <ion-content class="padding">
        <p translate>Bitte Teilnehmercode eingeben:</p>

        <p translate>Den Teilnehmercode erhalten Sie von Ihrem Betreuer.</p>

        <form class="list" name="loginForm" ng-submit="loginForm.$valid && login(loginForm)">
            <label class="item item-input item-stacked-label">
                <span class="input-label" translate>Teilnehmercode</span>
                <input name="code" type="text"
                       ng-model="code.input"
                       ng-disabled="isProcessing"
                       required
                       placeholder="{{'Code' | translate}}">
                <span class="assertive" ng-show="error">
                    {{error | translate}}
                </span>
            </label>
            <label class="item item-input item-select">
                <div class="input-label" translate>
                    Kurstag
                </div>
                <select name="courseday"
                        ng-model="code.courseday"
                        ng-disabled="isProcessing"
                        ng-options="day.name for day in Weekdays.days"
                        required
                        >
                    <option value="" translate>Wähle Wochentag</option>
                </select>
            </label>
            <button type="submit" class="button button-balanced button-block"
                    ng-disabled="isProcessing || loginForm.$invalid ">Login
            </button>
        </form>
    </ion-content>
</div>

###It is triggered by:

  $ionicModal.fromTemplateUrl('templates/login.html', {
      scope: $scope,
      backdropClickToClose: false,
      hardwareBackButtonClose: false
    }).then(function (modal) {
      $scope.modal = modal;
      $scope.modal.show();
    });