GrayMatter Robotics Robotics Engineer interview questions

They did not make a phone call or video interview before the offline challenge. They gave me an offline challange with a 6 hours duration. I have completed it around 4-4.5 hours and my code was working. What happened next is denial. If I completed the offline challenge correctly, why wouldn't you have progress with an interview? If you would reject my application in the first place, why would you give me an offline challenge? They have no respect for job applicants.