EXCLUSIVE

Kim Fields isn't making her new 'Real Housewives of Atlanta' gig a priority, according to co-workers who find her impossible to work with ... due to an inflated ego.

Sources on set tell us some of Kim's co-stars are livid she's been showing up late and leaving early for shoots. In one case, we're told she left Kandi Burruss' baby shower early -- during taping -- so she could help her kids do math homework.

Also, when they were filming in Jamaica, Kim showed up with her kids even though producers told the cast absolutely NO KIDS.

We're told Kim acts like she's better than everyone else, and still in her '80s heyday of 'Facts of Life.' Sources close to Kim say that's way off base, and she's a "consummate pro" who works with producers to ensure she meets her responsibilities to work and family. They also point out she shows up for every shoot on time and in good spirits.