Crohn's disease affects each patient differently. Depending on what part of the gut is being attacked [1], different digestive processes are implicated. That will lead to different kinds of foods being potentially problematic (as well as leading to a need for different kinds of supplementation).
The bottom line is: your mileage WILL vary.
(I've had Crohn's for nearly 45 years, since I was an adolescent.)
[1] My doc once told me about a patient he had that was affected in the throat!
ETA: for my personal experience, the one thing I can't eat is whole-kernel corn in any non-trivial quantity. It actually clogs me up. Oddly, popcorn is perfectly fine, as are corn tortillas and the like. It's happened to me twice. The first time I went to the ER and said I thought I had an obstructed bowel, and the admitting nurse said "can't be, if that were the case, you wouldn't be able to walk in yourself". I think that gives some perspective about what kinds of pain you can get used to. Second time it happened, I didn't bother, since there turned out to be nothing the ER docs could do other than monitor me. I just let it work itself out over the course of a couple days.
