NavigationDrawer and Nested Navigation Graphs: A problem scenario

Case of problem:

In this situation, all rectangles are graphs and arrows represents actions. The start navigation of graphs are given by the blue nested graph. The problem occurs in the navigation drawer's menu. My top-level destinations are A1, B1, A2 and B2. When I set menu like:

<menu>
    <item
        android:id="@+id/navigationGraphA1"
        android:title="A1" />
    <item
        android:id="@+id/navigationGraphB1"
        android:title="B1" />
    <item
        android:id="@+id/navigationGraphA2"
        android:title="A2" />
    <item
        android:id="@+id/navigationGraphB2"
        android:title="B2 />

</menu>

This don't work. No errors are generated, only when clicking on the menu, the navigation drawer does not forward to the corresponding screen.

To correct this, I done:

<menu>
    <item
        android:id="@+id/navigationGraphP1"
        android:title="A1" />
    <item
        android:id="@+id/navigationGraphB1"
        android:title="B1" />
    <item
        android:id="@+id/navigationGraphP2"
        android:title="A2" />
    <item
        android:id="@+id/navigationGraphB2"
        android:title="B2" />
</menu>

I don't know why, but in this way, navigation drawer works correctly.