menu - Android Navigation Drawer not showing SOME items -

my problem pretty awkard: have menu used in navigationview. problem in preview , in running application, items in menu , items in drawer different.

this menu activity_main_drawer

<?xml version="1.0" encoding="utf-8"?> <menu xmlns:android="http://schemas.android.com/apk/res/android">      <group>         <item             android:visible="true"             android:id="@+id/navitemhomepage"             android:icon="@drawable/ic_home"             android:title="home" />     </group>      <item         android:id="@+id/navmenuinterventions"         android:visible="true"         android:title="interventi">         <menu>             <item                 android:id="@+id/navitemmyinterventions"                 android:icon="@drawable/ic_interventions"                 android:title="miei" />             <item                 android:id="@+id/navitemunplannedint"                 android:icon="@drawable/ic_unplanned"                 android:title="non pianificati" />             <item                 android:id="@+id/navitemassign"                 android:icon="@drawable/ic_assign"                 android:title="assegna" />             <item                 android:id="@+id/navitemvalidate"                 android:icon="@drawable/ic_check"                 android:title="valida" />             <item                 android:id="@+id/navitemnewodl"                 android:icon="@drawable/ic_add"                 android:title="nuovo odl" />         </menu>     </item>      <item         android:id="@+id/navmenuwarehouse"         android:visible="true"         android:title="magazzino">         <menu>             <item                 android:id="@+id/navitemstocks"                 android:icon="@drawable/ic_warehouse"                 android:title="giacenze" />             <item                 android:id="@+id/navitemcharge"                 android:icon="@drawable/ic_load"                 android:title="carica materiali" />             <item                 android:id="@+id/navitemuncharge"                 android:icon="@drawable/ic_unload"                 android:title="scarica materiali" />         </menu>     </item>      <item         android:id="@+id/navmenusync"         android:visible="true"         android:title="sincronizzazioni">         <menu>             <item                 android:id="@+id/navitemsync"                 android:icon="@drawable/ic_sync"                 android:title="sincronizza anagrafiche" />             <!--<item-->             <!--android:id="@+id/navitemsync"-->             <!--android:title="sincronizza interventi"/>-->         </menu>     </item>     <item         android:id="@+id/navmenualerts"         android:visible="true"         android:title="avvisi">         <menu>             <item                 android:id="@+id/navitemalerts"                 android:icon="@drawable/ic_alert"                 android:title="avvisi" />             <item                 android:id="@+id/navitemnewalert"                 android:icon="@drawable/ic_add"                 android:title="nuovo avviso" />         </menu>     </item>     <item         android:id="@+id/navmenutimbs"         android:visible="true"         android:title="timbrature">         <menu>             <item                 android:id="@+id/navitemtimbs"                 android:icon="@drawable/ic_timb"                 android:title="timbrature" />         </menu>     </item>      <item         android:id="@+id/navmenuother"         android:visible="true"         android:title="altro">         <menu>             <item                 android:id="@+id/navitemsettings"                 android:icon="@drawable/ic_settings"                 android:title="impostazioni" />              <item                 android:id="@+id/navitemlogout"                 android:icon="@drawable/ic_logout"                 android:title="logout" />         </menu>     </item>  </menu> 

and use in main activity navigation drawer.

by using preview in menu file, can see correctly information can see below (sorry italian titles):

and main activity code (with navigationview)

<?xml version="1.0" encoding="utf-8"?> <android.support.v4.widget.drawerlayout 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:background="@drawable/background_light_grey"     android:id="@+id/drawer_layout"     android:layout_width="match_parent"     android:layout_height="match_parent"     android:fitssystemwindows="true"     tools:opendrawer="start">      <view         android:layout_width="0dp"         android:layout_height="0dp"         android:focusable="true"         android:focusableintouchmode="true"         />     <include         layout="@layout/app_bar_main"         android:layout_width="match_parent"         android:layout_height="match_parent"         app:layout_behavior="@string/appbar_scrolling_view_behavior"  />      <android.support.design.widget.navigationview         android:id="@+id/nav_view"         android:layout_width="wrap_content"         android:layout_height="match_parent"         android:layout_gravity="start"         android:fitssystemwindows="true"         app:headerlayout="@layout/nav_header_main"         app:menu="@menu/activity_main_drawer" />  </android.support.v4.widget.drawerlayout> 

but, when using preview, see (it misses "magazzini" , "avvisi" menus)

and in running application don't see both "magazzini" , "avvisi" menues.

anyone has idea why 2 menues not visible in application? copy-pasted each other don't why preview hiding 2 of them.

thanks