I'm posting this not because I think it'll get fixed, but because it might help someone else who is having this problem. It's cost me HOURS of time. Basically, if you update the footprint of a component that is already used in your schematic, you need to find every instance of that component, right-click it and select 'Update From Library' one-by-one. After you've done all of those, THEN go to your PCB layout and select Import Changes. If you try to use a faster method, like selecting all of the schematic parts that have been updated and using 'Update From Library' once (which, let's be honest, is the obvious way to do it), when you click Import Changes in your PCB, it will either not update anything or completely remove EVERY COMPONENT YOU HAVE PLACED. Remember, if EasyEDA borks your project, you can select an 'Historical record' from Project tab>Your name>Your project>Your schematic>right-click.