In the layout\m3expressive_alert_dialog.xml file, it adds android:filterTouchesWhenObscured="true" to the top androidx.appcompat.widget.AlertDialogLayout view.
The filterTouchesWhenObscured attribute should not be added to keep the consistent behavior as the system or AppCompat AlertDialog.
com.google.android.material:material:material 1.14.0-alpha04
layout\m3expressive_alert_dialog.xml
<androidx.appcompat.widget.AlertDialogLayout
xmlns:android="http://schemas.android.com/apk/res/android"
xmlns:app="http://schemas.android.com/apk/res-auto"
android:id="@+id/parentPanel"
android:layout_width="match_parent"
android:layout_height="wrap_content"
android:gravity="start|left|top"
android:orientation="vertical"
android:clipChildren="true"
android:filterTouchesWhenObscured="true"> <--- don't add this