Load attached FXML where root AnchorPane has reference to non-existing CSS file.
Try to display the Properties of the AnchorPane.
Inspector content is not drawn completely -- see screenshot
and following exception is raised:

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: Invalid Stylesheet file:/invalid/path/Stylesheet.css
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.CssUtils.getStyleClasses(CssUtils.java:125)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.CssUtils.getSingleFxObjectClasses(CssUtils.java:110)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.CssUtils.getFxObjectClasses(CssUtils.java:83)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.CssUtils.getStyleClasses(CssUtils.java:70)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.StyleClassEditor.getNewStyleClassItem(StyleClassEditor.java:80)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.editors.StyleClassEditor.<init>(StyleClassEditor.java:75)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.makeOrResetPropertyEditor(InspectorPanelController.java:1505)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.makePropertyEditor(InspectorPanelController.java:1425)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.getPropertyEditor(InspectorPanelController.java:1207)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.getInitializedPropertyEditor(InspectorPanelController.java:663)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.buildSection(InspectorPanelController.java:646)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.buildExpandedSection(InspectorPanelController.java:566)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.rebuild(InspectorPanelController.java:538)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.updateInspector(InspectorPanelController.java:492)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.InspectorPanelController.editorSelectionDidChange(InspectorPanelController.java:407)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$4.changed(AbstractPanelController.java:195)
at com.oracle.javafx.scenebuilder.kit.editor.panel.util.AbstractPanelController$4.changed(AbstractPanelController.java:192)
at com.sun.javafx.binding.ExpressionHelper$Generic.fireValueChangedEvent(ExpressionHelper.java:347)
at com.sun.javafx.binding.ExpressionHelper.fireValueChangedEvent(ExpressionHelper.java:80)
at javafx.beans.property.IntegerPropertyBase.fireValueChangedEvent(IntegerPropertyBase.java:106)
at javafx.beans.property.IntegerPropertyBase.markInvalid(IntegerPropertyBase.java:113)
at javafx.beans.property.IntegerPropertyBase.set(IntegerPropertyBase.java:146)
at com.oracle.javafx.scenebuilder.kit.editor.selection.Selection.incrementRevision(Selection.java:458)
at com.oracle.javafx.scenebuilder.kit.editor.selection.Selection.endUpdate(Selection.java:426)
at com.oracle.javafx.scenebuilder.kit.editor.selection.Selection.select(Selection.java:144)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.AbstractHierarchyPanelController.treeItemSelectionDidChange(AbstractHierarchyPanelController.java:568)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.AbstractHierarchyPanelController.access$000(AbstractHierarchyPanelController.java:88)
at com.oracle.javafx.scenebuilder.kit.editor.panel.hierarchy.AbstractHierarchyPanelController$1.onChanged(AbstractHierarchyPanelController.java:161)
at com.sun.javafx.collections.ListListenerHelper$SingleChange.fireValueChangedEvent(ListListenerHelper.java:158)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:72)
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.callObservers(ReadOnlyUnbackedObservableList.java:75)
at javafx.scene.control.MultipleSelectionModelBase$3.onChanged(MultipleSelectionModelBase.java:88)
at com.sun.javafx.collections.ListListenerHelper$Generic.fireValueChangedEvent(ListListenerHelper.java:315)
at com.sun.javafx.collections.ListListenerHelper.fireValueChangedEvent(ListListenerHelper.java:72)
at com.sun.javafx.scene.control.ReadOnlyUnbackedObservableList.callObservers(ReadOnlyUnbackedObservableList.java:75)
at javafx.scene.control.MultipleSelectionModelBase.clearAndSelect(MultipleSelectionModelBase.java:315)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.simpleSelect(TreeCellBehavior.java:284)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.doSelect(TreeCellBehavior.java:267)
at com.sun.javafx.scene.control.behavior.TreeCellBehavior.mousePressed(TreeCellBehavior.java:129)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:95)
at com.sun.javafx.scene.control.skin.BehaviorSkinBase$1.handle(BehaviorSkinBase.java:89)
at com.sun.javafx.event.CompositeEventHandler$NormalEventHandlerRecord.handleBubblingEvent(CompositeEventHandler.java:218)
at com.sun.javafx.event.CompositeEventHandler.dispatchBubblingEvent(CompositeEventHandler.java:80)
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.CompositeEventDispatcher.dispatchBubblingEvent(CompositeEventDispatcher.java:59)
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.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
at com.sun.javafx.event.EventDispatchChainImpl.dispatchEvent(EventDispatchChainImpl.java:114)
at com.sun.javafx.event.BasicEventDispatcher.dispatchEvent(BasicEventDispatcher.java:56)
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.Scene$MouseHandler.process(Scene.java:3684)
at javafx.scene.Scene$MouseHandler.access$1800(Scene.java:3409)
at javafx.scene.Scene.impl_processMouseEvent(Scene.java:1671)
at javafx.scene.Scene$ScenePeerListener.mouseEvent(Scene.java:2462)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:314)
at com.sun.javafx.tk.quantum.GlassViewEventHandler$MouseEventNotification.run(GlassViewEventHandler.java:243)
at java.security.AccessController.doPrivileged(Native Method)
at com.sun.javafx.tk.quantum.GlassViewEventHandler.handleMouseEvent(GlassViewEventHandler.java:345)
at com.sun.glass.ui.View.handleMouseEvent(View.java:526)
at com.sun.glass.ui.View.notifyMouse(View.java:898)
Caused by: java.io.FileNotFoundException: /invalid/path/Stylesheet.css (No such file or directory)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.java:131)
at java.io.FileInputStream.<init>(FileInputStream.java:87)
at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:90)
at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:188)
at java.net.URL.openStream(URL.java:1038)
at com.sun.javafx.css.parser.CSSParser.parse(CSSParser.java:245)
at com.oracle.javafx.scenebuilder.kit.editor.panel.inspector.CssUtils.getStyleClasses(CssUtils.java:123)
... 78 more