My experience has shown the main reason for not passing on the first try is a long delay from the Boot Camp to the exam date. Sadly, many people complete a Boot Camp but don’t get their application turned in immediately. “I’ll do it Saturday” becomes “I’ll submit it next weekend” which becomes “I’ll get to it after the holidays…” Think about the likelihood of passing a calculus exam 6 months after your last calculus class. Procrastination does you no favors. It’s not a good plan for success.
A second reason is that students didn’t take the exam seriously. Even though I emphasize the rigor of the exam, some students think they can rely primarily on their prior PM experience and/or education to get through the exam successfully. It won’t. It doesn’t. It takes effort to prepare for the exam and the effort must be directed to the right material.