Kotlin 导航架构组件 未生成 DestinationFragmentArgs

I have this in app gradle:

apply plugin: 'androidx.navigation.safeargs'

implementation 'android.arch.navigation:navigation-fragment-ktx:1.0.0'
implementation 'android.arch.navigation:navigation-ui-ktx:1.0.0'

在gradle项目中:

classpath 'android.arch.navigation:navigation-safe-args-gradle-plugin:1.0.0'

the navigation graph:

<navigation xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/navigation_graph"
    app:startDestination="@id/loginPhoneNumberFragment">

    <fragment
        android:id="@+id/loginPhoneNumberFragment"
        android:name="...fragments.LoginPhoneNumberFragment"
        android:label="@string/login_activity_title"
        tools:layout="@layout/fragment_login_phone_number">
        <action
            android:id="@+id/action_loginPhoneNumberFragment_to_loginCodeFragment"
            app:destination="@id/loginCodeFragment">
            <argument
                android:name="prefix"
                app:argType="string" />
            <argument
                android:name="phone_number"
                app:argType="string" />
        </action>
    </fragment>

    <fragment
        android:id="@+id/loginCodeFragment"
        android:name="...LoginCodeFragment"
        android:label="@string/login_activity_title"
        tools:layout="@layout/fragment_login_code" />

</navigation>

LoginPhoneNumberFragment:

val action = LoginPhoneNumberFragmentDirections.actionLoginPhoneNumberFragmentToLoginCodeFragment(prefix, phoneNumber)
view?.findNavController()?.navigate(action)

LoginCodeFragment:

override fun onViewCreated(view: View, savedInstanceState: Bundle?) {
        super.onViewCreated(view, savedInstanceState)

        val prefix = LoginCodeFragmentArgs.fromBundle(arguments).prefix //LoginCodeFragmentArgs is not recognized

    }

在LoginPhoneNumberFragment中，它创建了"LoginPhoneNumberFragmentDirections"类，但是在目标类LoginCodeFragment上，它不识别"LoginCodeFragmentArgs".

有人能告诉我我错过了什么吗？ (我清理和重建了缓存，并try 了无效缓存.)