I see. And i think i found the cause. We have removed the Blender menus in the node editor, and replaced it by our own. The old Blender menu is still there under the hood. But not longer accessible from the UI. To make it accessible again would mean to revert the node editor to the Blender state. No icons, a gazillion tabs to get lost … The port to 2.8 will not change this situation. Sorry that i have no better news 
You could theoretically add nodes by the search menu in the Add menu item in the header. This one still accesses the old code. But i haven’t tested it.