There are some people within the movie industry who believe that Katherine Heigl is a little hard to work with, but is that really the case, or is she just honest about the work she does? The perception of her is largely down to an interview she gave about her part as Alison Scott in 'Knocked Up,' back in 2007. The idea of an interview is to talk up the movie you're in, and give people a reason to want to see it. Heigl took the opposite approach.
In Heigl's own words, the film was 'a little sexist.' She didn't like the fact that her character was portrayed as dull and joyless, whereas Seth Rogen was just a regular guy trying to get on with his life. Perhaps understandably, she felt like the film was unkind to women in general, and so she found it hard to enjoy the film. She's had a long time to reflect on her remarks, and issued a partial apology in 2016, saying she'd intended no disrespect to Rogen or his work. For his part, Rogen accepted the apology with grace.