at 15:15, I cannot drag the sun/rays OR the Mountains. I do exactly like you are doing, but my mountains are not moving, only the waves and trees. Strange, and super annoying. I figured it out! It won't grab anything that is still Grouped. If you ungroup everything, it will then allow you to select and move as you have shown. Any Grouped item can not be selected with the node tool in this way to be adjusted with the other ungrouped items. Hope this helps someone else. Keep the tutorials coming!