Kitware HR Generalist interview questions

Had an initial phone interview. I was invited back for a second round of interviews. I was to be there for most of the day. I had to give a 20 minute presentation about myself, my skills and my experience. The conference room I was in had approximately 30+ people in the room who all had opportunities to ask questions. Then I interviewed with the entire management team totaling 4 additional people each one on one. They took me to lunch with 3 other peers. Of course more questions and more getting to know me. Then a last round of a one on one interview with the hiring manager. I did not get the job. I emailed the hiring manager thanking him for the opportunity but also asked for some feedback on why I was not the ideal candidate. He never returned my email! I took a day off from my current job for this interview not to mention the time I spent putting together a presentation for a large number of people. He could have told me anything and it would have been fine. He never replied. Not only unprofessional but rude. I will never forget how unreasonable that experience was for me. The position was not a high level role, it was for HR Generalist so I have no idea why I was put through that kind of rigorous process. Obviously a huge red flag as an employer.