Okay - so I solved my own problem!!! I'll post the answer here for future reference because it isn't necessarily intuitive. You have go to Sync Content. So see the button circled below:
76% of original size (was 664x19) - Click to enlarge
Click that button and go down to Sync Installed Assets. Click that and IF you've already installed the content using RLDownloader then this will work.
I love it when I answer my own question.