Sam, Nick and Charles stopped working together for a long time after World Peace. Nick and Charles did try to pitch a TV show to AS that Sam wasn't part of. That stuff ruins friendships. I don't think it's an unbelievable scenario that their friendship was strained after Sam got World Peace cancelled. But people need to remember that Sam single handedly kept the MDE brand alive after all that while they scurried off and did their own things.
Channing made a point to play the video of Charles calling Sam a bad friend, etc but she had her own personal reasons for doing so, which she outlined clearly:
Sam didn't want her working with Charles or Nick after World Peace. She was employed by Sam and he wouldn't put her or any of his employees in contact with the other two members of MDE, which made her mad. Why did it make her mad? Probably because she was hoping to get a job with them and quit working for Sam. It's really pretty obvious why Sam wanted to avoid that scenario. She made it sound so nefarious and evil but she was just being a dumb bitch as usual.