Oprah Winfrey announced yesterday that she would no longer be producing a documentary following the lives of alleged "victims" claiming sexual assault by music industry mogul Russell Simmons.

Well now MTO News is getting some details about WHY Oprah is backing away from the film.

According to one person who saw the new documentary - the allegations against Russell are "thin" on evidence, and the victim's stories seem to have "discrepancies."

Since the start of the allegations, Russell Simmons has come out publicly and denied ever sexually assaulting anyone.

The insider told MTO News, "After the disaster of Oprah putting out the unsubstantiated claims against Michael Jackson in Leaving Neverland, she couldn't be a part of this."

The insider added, "You can't make those kind of allegations with no proof whatsoever. If Oprah put her name behind that, her reputation would be ruined."

Our insider added, "Those women may have been assaulted, I can't say. But that documentary doesn't prove sh*t."

TMZ is reporting that Oprah is "stepping down as executive producer AND blocking [the documentary's] path to Apple TV!"

The doc is still set to premiere next month at the Sundance Film Festival.

In a statement, Oprah said:

“I have decided that I will no longer be executive producer on The Untitled Kirby Dick and Amy Ziering documentary and it will not air on Apple TV+," Winfrey said in a statement to The Hollywood Reporter. "First and foremost, I want it to be known that I unequivocally believe and support the women. Their stories deserve to be told and heard. In my opinion, there is more work to be done on the film to illuminate the full scope of what the victims endured, and it has become clear that the filmmakers and I are not aligned in that creative vision. Kirby Dick and Amy Ziering are talented filmmakers. I have great respect for their mission but given the filmmakers’ desire to premiere the film at the Sundance Film Festival before I believe it is complete, I feel it’s best to step aside. I will be working with Time’s Up to support the victims and those impacted by abuse and sexual harassment.”