Senior SE: HR conversation + engineer coding challenge (solved in 20 min); then HR went silent for 2 months

Had first two rounds which went amazing - solved the coding challenge in 20 minutes and the interviewer was impressed. First round was with HR - a normal conversation. Second was with an engineer and a coding challenge. After emailing HR multiple times, they never got back. It's been 2 months and even then, no reply from HR. What a waste of time for 2 interviews.