EDIT

Clicking on "New" does not open submenu.

This might be related to changes in feature tree editor.

Also creating a new Factual Data Set (DescriptionBase) afterwards throws an NPE:

login : admin
editor version : 4.8.0.201706140848
server : test.e-taxonomy.eu (edit-test) / rem_conf_am
schema version : 4.7.0.0.201710040000
os : Windows Server 2012 R2 6.3 amd64
java : 1.8.0_121
java.lang.NullPointerException
    at eu.etaxonomy.taxeditor.editor.view.descriptive.handler.DynamicFeatureMenu$1.fill(DynamicFeatureMenu.java:68)
    at org.eclipse.ui.actions.CompoundContributionItem.fill(CompoundContributionItem.java:67)
    at org.eclipse.ui.internal.menus.DynamicMenuContributionItem.fill(DynamicMenuContributionItem.java:147)
    at org.eclipse.jface.action.MenuManager.doItemFill(MenuManager.java:728)
    at org.eclipse.jface.action.MenuManager.update(MenuManager.java:810)
    at org.eclipse.jface.action.MenuManager.handleAboutToShow(MenuManager.java:472)
    at org.eclipse.jface.action.MenuManager.access$1(MenuManager.java:465)
    at org.eclipse.jface.action.MenuManager$2.menuShown(MenuManager.java:497)
    at org.eclipse.swt.widgets.TypedListener.handleEvent(TypedListener.java:256)
    at org.eclipse.swt.widgets.EventTable.sendEvent(EventTable.java:84)
    at org.eclipse.swt.widgets.Display.sendEvent(Display.java:4418)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1079)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1103)
    at org.eclipse.swt.widgets.Widget.sendEvent(Widget.java:1084)

This might be related therefore I put it into the same ticket.