Raven-Symoné has told Demi Lovato she wasn't "the nicest person" when they first met

Speaking in the documentary, Demi said: "When we first got on the phone to talk about this project.

"I was like, 'I watched you on 'That's So Raven'. Such an inspiration.' You were like, 'B****, I was on your show.' I was like, 'Oh my god, she was.' "

The 32-year-old star struggles to remember a lot of that period in her life because of her dissociation, a disorder which the American Psychiatric Association notes can cause forgetfulness as a result of past trauma.

She acknowledged she was "difficult" to work with because she was "in so much pain" and "hurting".

Raven - who guest starred as Amber Algoode on 'Sonny With A Chance' in 2010 - recalled: "I mean, you weren't the nicest person. You weren't like, 'Welcome!' You weren't doing that."

However, the 38-year-old star understood the pressures of being a child actor, and "didn't hold it against" her.

She added: "Being the type of person I am and that I've been in the industry for as long as you, and I understand the glaze over the eyes.

"I didn't hold it against you. I just was like, 'Something's going on there.'"

Elsewhere in the documentary, 'Cool For The Summer' singer Demi noted that when her career blew up after 'Camp Rock' in 2008, it meant there was a dynamic shift for the second film, which impacted her friendship with her castmates.

Speaking to co-star Alyson Stoner, she recalled "trading connection for success" at the time.

And Alyson, 31, replied: "It felt so hard to access you in that way. We had lost that thread of trust, we had lost that closeness.

"The last few years of working together felt really challenging. I do remember a sense of walking on eggshells. There was definitely a lot of fear of a blowup."

Although Demi acknowledged everyone was "going through" their own issues behind the scenes, it wasn't an "excuse to treat anyone poorly".

She told Alyson: "I just want to genuinely, deeply apologise for any stress or any walking on eggshells, any hurt feelings.

"I'm genuinely so sorry for that. And I look back at that time and I have profound sadness because I'm like, 'How many people did I treat poorly?'"