A couple of things to try, make sure your oven is not too hot and not too cool, many ovens do not accurately. Purchase an oven thermometer to be sure. You might have also overworked the dough, be sure to bring dough together until just combined. Instead of separating the scones completely, cut through them and use the bench scraper to just barely pull the scone away from the other one, this will give structure and rise to the scone, though you may need to bake a few additional minutes.