These songs (‘Loving You’, ‘Monkey Business’, ‘She's Trouble’, ‘Another Day’, ‘Behind The Mask’
were not forgotten almost immediately after they were recorded, even though they all contain complete vocals.
Michael Jackson found these songs good enough (that is why he fully recorded his vocals on them), but he shelved them for other reasons.
For example, he did want to release ‘Behind The Mask’, but song-writers’ copyright issues did not let that happen.
‘Monkey Business’ was a song that again he found it good enough, but this song simply did not fit the theme of his ‘Dangerous’ album.
‘Another Day’ was also another song that he found it good enough, but this song simply did not again fit the theme of his ‘Invincible’ album.
Note here what Bruce Swedien said about that matter: many songs that Michael Jackson found good enough and thus he recorded his complete vocals on them, they did not make a certain studio as long as they did not fit the cohesion and the overall drama of the album.
Also, Michael Jackson kept changing producers and songwriters in his final years (will.i.am, Neff-U, RedOne, Ne-Yo, etc) very easily because he was not satisfied with the songs (that these people were submitting to him) in order to fully record his vocals on them.