NetEdge Computing Solutions interview questions

I had an interview scheduled with them and arrived on time. After waiting for two hours, they conducted an introductory round and then informed me that I needed to take a written assessment, with a cutoff of 17/30 and a minimum requirement of 13/30 to move to the next round. I scored 28/30 in the assessment, but afterward, they focused on another candidate (whom I suspect might be a relative), who scored only 12/30. They rescheduled his assessment and interview. I waited for over an hour in the reception, and eventually, the receptionist told me I could leave, with results to be updated by phone. The next day, I received a call saying my resume was not shortlisted. My question is, if my resume wasn’t shortlisted, why was I selected for the first interview and assessment? The cutoff for the next round was 13/30, and I cleared it with 28/30. Is this a mistake? I don’t think so.