When including custom .fxml files with scenebuilder 2.0 the hierarchy/controller view stops working.
The following error is logged:
java.lang.ClassCastException: com.oracle.javafx.scenebuilder.kit.fxom.FXOMIntrinsic cannot be cast to com.oracle.javafx.scenebuilder.kit.fxom.FXOMInstance
at com.oracle.javafx.scenebuilder.kit.metadata.util.DesignHierarchyMask.getColumnsSize(DesignHierarchyMask.java:767)
at com.oracle.javafx.scenebuilder.kit.metadata.util.DesignHierarchyMask.getClassNameInfo(DesignHierarchyMask.java:234)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.HierarchyItem.getClassNameInfo(HierarchyItem.java:264)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateLayout(HierarchyTreeCell.java:812)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateItem(HierarchyTreeCell.java:518)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.treeview.HierarchyTreeCell.updateItem(HierarchyTreeCell.java:114)
at javafx.scene.control.TreeCell.updateItem(TreeCell.java:509)
at javafx.scene.control.TreeCell.indexChanged(TreeCell.java:474)
at javafx.scene.control.IndexedCell.updateIndex(IndexedCell.java:115)
at com.sun.javafx.scene.control.skin.VirtualFlow.setCellIndex(VirtualFlow.java:1792)
at com.sun.javafx.scene.control.skin.VirtualFlow.addTrailingCells(VirtualFlow.java:1211)
at com.sun.javafx.scene.control.skin.VirtualFlow.layoutChildren(VirtualFlow.java:1102)
.....
I will try to attach the logfile as well as an two example .fxml files.

Child.fxml:
<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>

<GridPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" prefHeight="400.0" prefWidth="600.0" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8">
  <columnConstraints>
    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
  </columnConstraints>
  <rowConstraints>
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
  </rowConstraints>
   <children>
      <Label text="Label" GridPane.rowIndex="1" />
      <TextField GridPane.columnIndex="1" GridPane.rowIndex="1" />
   </children>
</GridPane>

Parent.fxml:
<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.*?>
<?import java.lang.*?>
<?import javafx.scene.layout.*?>

<GridPane maxHeight="-Infinity" maxWidth="-Infinity" minHeight="-Infinity" minWidth="-Infinity" xmlns:fx="http://javafx.com/fxml/1" xmlns="http://javafx.com/javafx/8">
  <columnConstraints>
    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
    <ColumnConstraints hgrow="SOMETIMES" minWidth="10.0" prefWidth="100.0" />
  </columnConstraints>
  <rowConstraints>
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
    <RowConstraints minHeight="10.0" prefHeight="30.0" vgrow="SOMETIMES" />
  </rowConstraints>
   <children>
      <fx:include source="child.fxml" GridPane.columnIndex="1" GridPane.rowIndex="2" />
   </children>
</GridPane>

Opening the parent fails.
This seems to happen when including a GridPane into another.
When I wrap the included gridpane into a StackPane everything works fine.