Heartbeat Medical Solutions interview questions

The most weird process, I've ever experienced. I had three interviews for a senior management role. With exception of the first HR screening, other calls were supposed to be with the people who were in the current role, but were about to leave. Not a single a call with any of the future stakeholders. With a request for a third call, which was supposed to be a case study, I raised the topic about not having spoken with my future boss, I got a reply that they have such a process. During the third call, one of the interviewers has not come for the interview. So it was more or less the same people as in the interview Nr 2. After that a rejection came without any explanation, while all the calls were positive.

2 rounds using Google hangouts. First round was initial discussion with the HR. Second round was discussion with one of the founder(who was supposedly doing QA) and a backend engineer. They gave a task to design/ prepare a Test plan for a complex medical workflow feature which was very abstract and with minimum details. The interviewers were friendly and the HR was responsive to all the emails. I prepared the tasks which obviously took more time than they suggested. They said that all the questions shall be discussed after my submission in the next round and hence I made some assumptions to complete my tasks. However, after 10 days of my task submission I received an email that I was rejected with no good reason. I advice the recruitment team to define proper tasks to assess an individuals skills.