ng-dropdown-multiselect不允许选择

Question

我在一个新表单上有两个ng-dropdown-multiselect下拉列表（从它们在另一表单上工作的地方复制的代码）。两者都正确加载了数据，但将鼠标悬停在同样呈灰色的复选框上时，错误地显示了general prohibition符号。这些多选选项之一使我无论如何都可以选中复选框，而另一个则不能。我在某处缺少一些财产吗？

HTML：

<td>
    <div ng-dropdown-multiselect=""
         title="Select the roles"
         ng-disabled="!vm.hasAccess"
         name="roles"
         translation-texts="{dynamicButtonTextSuffix:'role(s)'}"
         options="vm.data.roles"
         selected-model="user.roles"
         checkboxes="true"
         nopadding="true"
         extra-settings="roleDropdownSettings">
    </div>
</td>
<td>
    <div ng-dropdown-multiselect=""
         title="Select the sites"
         ng-disabled="!vm.hasAccess"
         name="sites"
         translation-texts="{dynamicButtonTextSuffix:'site(s)'}"
         options="vm.data.sites"
         selected-model="user.sites"
         checkboxes="true"
         nopadding="true"
         extra-settings="roleDropdownSettings">
    </div>
</td>

TS：

$scope.roleDropdownSettings = {
            displayProp: "text",
            idProp: "value",
            scrollable: true,
            showCheckAll: false,
            showUncheckAll: false,
            closeOnBlur: true,
            externalIdProp: "" //makes the multi-select control return the full object instead of just the id value.
        };