Garageband extra sounds purchase. Where did they go?

Hey, I purchased the extra sounds n loops etc for Garageband after updating to 10.0.2. The app itself was working fine until I made this purchase. Now it won't open. The menu bar appears at the top of the screen but you can't select anything. I didn't see a box saying that the extras were downloading, the only result was that Garageband stopped working. In case it matters, I also have the older version of GB on my Mac and it's working fine.

Any advice greatly appreciated.

Thanks!