OneSec Deep Learning Engineer interview questions

Interviewer did not attend the scheduled introductory meeting without notifying it. Even though I have waited in the call for 25 mins, and e-mail the interviewer about it, I get no response. I believe this is very unprofessional. Also, I received invitation 6 months after completing the initial CV screening and coding, and personal assesment tests. All of these are sign of very unprofessional hiring process.