OTTO Data Engineer interview questions

In two different days we spent almost 8 hours (a full day) together, first call with 3 people (developer, data scientist and project manager) and second call with all team (about 12 people) for over 6 hours. They all shared positive impressions about the hiring day and said will turn back soon. In the long call they introduced their running system and asked me to detect some problems. I detected at least two quite obvious issues and they were quite happy with this contribution. But after this step, even though I insisted asking to their HR and some of the people who attended the interview, they never answered the emails or shared any update or feedback. This was a total disappointment for me.