Then there's a bug or something with the UI because sometimes I favorite something only for it to come up later and to check to see if it is favorited I un-favorite and then re-favorite it to check if it is but sometimes it marks it as if it it was never favorited to begin with.
If you could add a favorited icon to the top left corner of the screen under the money counter that would be a big help because with so many images it can be hard to remember what is and isn't favorited as there's no way to view the list of favorited images.