Lots of songs to clear on seasons 4-7, that much I know.
Okay , that explains a lot . Music clearance rights have also killed the release of the Warner Brothers Detective shows. It's shame that some type of compromise couldn't be worked out with the music publishing companies . For example in Britain there is one fee paid to cover all songs - it more economical so things are more easily released .Lots of very expensive music rights to clear. Not sure we will see this one continue.