This summer Lady Gaga surprised everyone when she showed up at the Pitchfork Music Festival in Chicago. Mother Monster was spotted side stage to support her friend and label mate Kendrick Lamar.

While Lamar told The Source Gaga’s “a real good friend,” it turns out the two were also working on new music together. At Kendrick’s listening party for good kid, M.A.A.d city last month MTV talked of the collaboration.

“On [‘Partynausous’] the Fame Monster sang of being a sinner, while Kendrick rapped about the changes around him and the new hangers-on he’s acquired since becoming more famous,” Rob Markman wrote.

But on the album, due for release October 22, you won’t be hearing that song. Lady Gaga took to Twitter and her social media network to explain why.

“I apologize to the fans that this situation with ‘Partynausous’ is confusing. To clear it up I must explain this. When I collaborate with an artist I work solely with them, not with their camps or management. It’s purely organic and creative,” she wrote. “I love Kendrick dearly as a friend, but was not willing to compromise musically to the changes his team was making to my music.”

Gaga went on to explain that this is why she won’t be heard on his upcoming release.

“I have a very specific vision as a producer and songwriter, and I always have,” she said. “That song will be released at a different time, for a different project . . . I think you should check out his stuff because he is truly great. He’s a good kid, its just sometimes a mad city.”

-Annie Reuter, CBS Local