I know the music industry, and although I have no concrete proof... I believe that Beyonce was the one who nipped this 'problem' in the bud.
Amerie was on Columbia just like Beyonce. Amerie dropped her first album, and it was well received and so she was given the green light by Columbia to do her. Well, that second album went hard... a little too hard. Cuz next thing you know, Beyonce is swagger jackin' Amerie. Remember that first Beyonce song featuring Jay-Z? Well, that was produced by Rich Harrison, who did Amerie's entire first album and the about half of her second album. If you listen to Crazy In Love and then listen to Amerie's go-go tracks... you'll see what I'm saying.
You know how when you are making an album, and you have to give it to the label.... and they take it, give a listen, then have to approve it? Well, for Amerie's third album, she did just that. The label however, took it... LEAKED IT to Beyonce, next thing you know Amerie's album is pushed back. Beyonce's album comes out and parts of it sounds like the mixtape Amerie had dropped because the label was f**king around. Then after that.... they decide not to even release Amerie's album in North America.
... and now she is no longer on Columbia and hasn't worked with Rich Harrison since her second album.
Amerie released a fourth album on Island/Def Jam. That got zero promotion but was still really good. She married her manager. He's obviously not a very good manager.