Ok, it may not be about Diana Ross in the first place, but I think it gives a great insight about what happened to her while at RCA.
From Kenny Rogers POV

Gibb’s perky, poppy “Islands in the Stream,” a duet by Rogers and Dolly Parton, was another smash hit -No. 1 country and pop – and the RCA era appeared to be off to a great start. Eyes That See in the Dark sold four million copies.
Not long after the album’s release, however, Bob Summer was fired from RCA. Rogers: “The new guy moves in, and I literally went into his office and said ‘Tell me what my future is here, now that Bob’s gone.’ He said “Well you’ve got a lot of money per album coming your way – if it were me I’d take it and go home.
“He said “But I can’t let you be successful. Because if I make you successful, it makes Bob Summer look good. And people are going to ask why they let him go if he made a good deal.’”
Translation: Don’t expect any promotion help from your label.
Scratching his head, Rogers went back to work. There was another Gambler TV movie, and a Christmas album with Dolly Parton, and 20 Greatest Hits, the first in a series of reissues and re-packagings from his old label.
Leaving a company where you’d been ably supported for years, Rogers believes, was probably not such a great idea. “When you’re in business, you negotiate for the better deal,” he says. “I don’t think I realized there could be a downside.” In retrospect, he calls the move to RCA a “huge mistake.” But he couldn’t ignore the money they waved at him.
Next out of the gate at RCA was “What About Me,” a middle-of-the-road ballad performed with both Kim Carnes [[they’d duetted on “Don’t Fall in Love With a Dreamer,” from Gideon, four years before) and R&B balladeer James Ingram.
“What About Me?” was the first warning sign that something was terribly wrong. Although the “trio” made the pop Top 20, their song bombed at country radio.
Hade he gone too far?
Know when to fold ‘em
He was to hit the jackpot two or three more times at country, but by 1987, Kenny Rogers had had his last Number One. He never came near the pop charts again.
“I think I had gotten too far away from my core base, which was country,” Rogers says. “You have to have a core group of people who follow you and defend you at all times. And the minute you offend those groups, they’re not easy to get back.
“At one time, if you had a country record you could be there forever. That was what attracted me to it.
“I think I made some strategic mistakes based on my own musical comfort level – and at that same time, country music was going much more country, so I was much farther out of the pocket.”