new code logic for saving tree.. should work fine even if the node positions fail

app/controllers/admin/items_controller.rb

@@ -24,7 +24,7 @@ class Admin::ItemsController < OrbitBackendController
 
   def update_position
     item = Item.find(params[:id])
-    item.shift_to(params[:parent_id], params[:position].to_i)
+    item.shift_to(params[:parent_id], params[:position].to_i, params[:next_sibling_id])
     render :nothing => true, status: 200
   end