I think the Apatow formula worked better on TV, tbh (note that I'm only counting the two movies he has directed himself, although some of the films he's produced/written sometimes have the same issues).
He kinda made his name with dramedies, which could get away with having a mostly funny episode and then capping it with a more sentimental scene, with the occasional full on sentimental episode. That works well in a TV show, but in a movie, you tend to either want something sentimental or something funny. And the problem is that both Knocked Up and The 40 Year Old Virgin have tons of laugh out loud bits, but when they go into sentimental high gear, it's kinda like "Hey, where did the funny go?" The change in tone is just jarring.