There's actually a lot more than those tracks missing. The boxset is fairly comprehensive but it's not pretending to be literally every mix ever. The idea was that it includes everything that was either unreleased, vinyl-only or rare, and then a selection of the best remaining mixes. But to fit everything on you would need probably 15 discs or something. So there's no big mystery why certain mixes weren't included.. if everyone made their own tracklisting each one would be different!