The "Invincible" Album came out in 2001
He didn't release any songs in 1999.
It was released in 2001.
He was probably working on his Invincible album which was released in 2001.
Songs of Azores - 2001 was released on: USA: 8 March 2001 (New York Underground Film Festival)
Michael Bell - 2001 was released on: USA: 23 January 2001 (Slamdance Film Festival)
Good Entertainment with Michael Medved - 2001 TV was released on: USA: 15 December 2001
Beyond the Glory - 2001 Michael Irvin was released on: USA: 21 July 2002
It was released in October 2001.
Michael Jackson 30th Anniversary Celebration - 2001 TV was released on: USA: 13 November 2001 Australia: 19 November 2001
Kong The Animated Series - 2001 Sacred Songs 1-36 was released on: USA: 30 April 2006
No, Michael has more than 300 songs recorded that have never been released, nor heard by the public.
He sings all of them.