Here's the proposed listing of release dates:

June 21st: “Around the World in A Day” (1985)
July 19th: “Parade (Under the Cherry Moon soundtrack)” (1986)
August 23rd: “Sign o’ the Times”(1987)
September 20th: “The Black Album” (1987 recorded; 1994 released)
October 18th: “Lovesexy” (1988) and “Batman” soundtrack (1989)
November 22nd: “Graffiti Bridge” soundtrack (1990) and “Diamonds and Pearls” (1991)
December 13th: “The Love Symbol” (1992)

As we're all aware, only the first 3 came out, and the rest were abounded. But why not look at the release underneath Sign? The Black Album, from what I heard was on Tidal for a bit under "NPG Records" (WB issued the 1994 release), but months later WB blocked that copy cause they needed to get their vinyl issue out, which they didn't. I don't know if the later is true, but I've heard that's also why TBA is not in the Sony deal (from my best estimation: For You-Prince-Dirty Mind-Controversy-1999-ATWIAD-Sign O The Times-Lovesexy-D&P-Love Symbol-Come-The Vault).

Later WB planned on a repilca of the Sexy MF picture disc for Record Store Day after the "angryness" above, but that also didn't come out ("There's no way why we're making an old picture disc rather than a newly-designed one!").

I have no idea as to the reason, although I'd love to know why. I wouldn't be surprised if the decision was made to hold back TBA for an RSD or other limited-edition release that they could make a big fuss of, but it looks like they've given up on doing anything with the others.

one reason could be that they decided they will reissue all of his WB era albums
in large or smaller boxsets like the 1999 reissue and couple those to new vinyls,
rematered and all.

Maybe it's because they got sent 4Ever and PR Deluxe.