Android Studio App Links Assistant no activity

Question

I am currently working on app linking, however when using the app links assistant, I can't choose any activity. Why is that and how can I fix it?enter image description here

I checked my AndroidManifest and I at least have a MainActivity

    <application
        android:name="${applicationName}"
        android:icon="@mipmap/ic_launcher"
        android:label="Example App"
        android:requestLegacyExternalStorage="true">
        <activity
            android:name=".MainActivity"
            android:configChanges="orientation|keyboardHidden|keyboard|screenSize|smallestScreenSize|locale|layoutDirection|fontScale|screenLayout|density|uiMode"
            android:exported="true"
            android:hardwareAccelerated="true"
            android:launchMode="singleTask"
            android:theme="@style/LaunchTheme"
            android:windowSoftInputMode="adjustResize">
            <!-- Specifies an Android theme to apply to this Activity as soon as
                 the Android process has started. This theme is visible to the user
                 while the Flutter UI initializes. After that, this theme continues
                 to determine the Window background behind the Flutter UI. -->
            <meta-data
                android:name="io.flutter.embedding.android.NormalTheme"
                android:resource="@style/NormalTheme" />

            <intent-filter>
                <action android:name="android.intent.action.MAIN" />
                <category android:name="android.intent.category.LAUNCHER" />
            </intent-filter>
            <meta-data
                android:name="flutter-deeplink"
                android:value="true" />
            <intent-filter android:autoVerify="true">
                <action android:name="android.intent.action.VIEW" />

                <category android:name="android.intent.category.DEFAULT" />
                <category android:name="android.intent.category.BROWSABLE" />

                <data android:scheme="https" />

                <data android:host="app.example.de" />
            </intent-filter>
        </activity>
        <!-- Don't delete the meta-data below.
             This is used by the Flutter tool to generate GeneratedPluginRegistrant.java -->
        <meta-data
            android:name="flutterEmbedding"
            android:value="2" />
    </application>

Also, when trying to check my app link with adb shell pm get-app-links com.example, I get verification state 1024.