How do I add custom images using Image Library Workshop in composer?

I've crated a bunch of symbols in Illustrator and exported them as JPG's. I wish to add these to my manuals but I cant see them when I open the 'Image Library' dock. I can see other JPG's in different folders (even larger images) and add them, no problem. Could I have exported them incorrectly? Does Composer have a problem with Illustrator created images? Is there a way to refresh the Image Library? What am I missing?!

Any help would be much appreciated.

SolidworksComposer