Open attached included1.fxml.
Then select the included object.
You will get assertion errors when invoking edit actions.

Exception in thread "JavaFX Application Thread" java.lang.AssertionError
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMLoader.endElement(FXOMLoader.java:291)
at javafx.fxml.FXMLLoader.processEndElement(FXMLLoader.java:2836)
at javafx.fxml.FXMLLoader.loadImpl(FXMLLoader.java:2526)
at javafx.fxml.FXMLLoader.load(FXMLLoader.java:2419)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMLoader.load(FXOMLoader.java:89)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.<init>(FXOMDocument.java:75)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMRefresher.refresh(FXOMRefresher.java:58)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.refreshSceneGraph(FXOMDocument.java:262)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMDocument.endUpdate(FXOMDocument.java:249)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMNodes.newDocument(FXOMNodes.java:230)
at com.oracle.javafx.scenebuilder.kit.fxom.FXOMArchive.<init>(FXOMArchive.java:56)
at com.oracle.javafx.scenebuilder.kit.metadata.util.ClipboardEncoder.makeEncoding(ClipboardEncoder.java:78)
at com.oracle.javafx.scenebuilder.kit.editor.EditorController.performCopy(EditorController.java:1526)
at com.oracle.javafx.scenebuilder.kit.editor.EditorController.performControlAction(EditorController.java:1187)
at com.oracle.javafx.scenebuilder.app.DocumentWindowController.performCopy(DocumentWindowController.java:1170)
at com.oracle.javafx.scenebuilder.app.DocumentWindowController.performControlAction(DocumentWindowController.java:536)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$DocumentControlActionController.perform(MenuBarController.java:1518)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController.handleOnActionMenu(MenuBarController.java:1074)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController.access$800(MenuBarController.java:88)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$20.handle(MenuBarController.java:1067)
at com.oracle.javafx.scenebuilder.app.menubar.MenuBarController$20.handle(MenuBarController.java:1063)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:49)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.scene.control.GlobalMenuAdapter$5.handle(GlobalMenuAdapter.java:158)
at com.sun.javafx.scene.control.GlobalMenuAdapter$5.handle(GlobalMenuAdapter.java:156)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:86)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:238)
at com.sun.javafx.event.EventHandlerManager.dispatchBubblingEvent(EventHandlerManager.java:191)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:58)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.EventUtil.fireEventImpl(EventUtil.java:74)
at com.sun.javafx.event.EventUtil.fireEvent(EventUtil.java:54)
at javafx.event.Event.fireEvent(Event.java:204)
at javafx.scene.control.MenuItem.fire(MenuItem.java:462)
at com.sun.javafx.tk.quantum.GlassSystemMenu$6.action(GlassSystemMenu.java:234)