OpenText UI Developer interview questions

I had 4 round of interviews. Although i am a ui developer, yet i was interviewed for backend too since i work in backend too. First round was UI round, questions from angular 2,4, html, css, bootstrap, plus some code writing. Second round was Java round, questions from core java, spring and hibernate, and some code writing. Third round was totally scenario based, questions related to several hacking, security. Final round was managerial round, where a manager took my interview and asked very common and simple questions, not related to coding at all. Interview went pretty well. I got selected. HR round was telephonic and i got my offer letter within a week.

On site interview with two managers from R&D department. Interview was good, I answered all the questions with analysis steps. But after that, I didn't get any responses for it. No offer obviously. I emailed the recruiter twice, they didn't even say a word about the interview. The HR team is so unprofessional.