Amazon Web Services Sr. Solutions Architect interview questions

AWS requested quite a long homework (5 hours one). On top of this, there is a long preparation for the interview and then at least 5 hours of interview. In total, this was 14 hours of investment. During the whole process I was said everything great, homework succeeded with flying color, answered all questions with very positive feedback. At the end I was said that I did not succeed without any detail ... I find it quite unfair when one spent so much time in preparing an interview, so little feedback to get back.