Why will a DJ mix album contain all the single tracks, but not the included fully mixed track?

[joshimal]

Many DJ mix albums that I'd like to listen to contain all the tracks available to play. Obviously Spotfiy has listen for each of the tracks. But often there is a grayed out "full hour+ mix" of all the tracks. Why can you not play that mix if all tracks are available.

Additionally, I tried Apple Music when it was first introduced, and it allowed users to listen to the full length DJ mixes that I can't listen to on Spotify. Some of the albums will even have unlicensed tracks diplayed in gray, but you can still play the full mix.

Any thoughts?