An option to not hide, but show an action button in disabled mode.
I can set a Y/N condition to show/hide the button, like have filled all the fields in that row (for example), or have at least 10 child rows, but the user might not now that and might not know what to do next and get stuck.
If the user can see a button but he cannot click (maybe in a different color - light grey), he will realize that he must do something to enable that button, improving the user-experience.