Sendwave Senior Software Developer interview questions

First it is a screening video call, you get to know about the company and you discuss your professional background. After that you are given a home task. When you're done, they review your project and, if ok, arrange a string of face-to-face interviews, that lasts 3.5 hours. All of those are done via video conference call since the company is 100% remote. First is the presentation about the project you've built in the previous step that you give to a panel. After that you have an interview with a technical team member and another one with a manager. They close with a 30-min culture fit interview. I was pretty happy with all the technical aspects of the process. And they seemed too. From the conversation with a tech team member it seemed their codebase and dev practices could be improved tremendously. My home task and the presentation clearly showed how the business could benefit from the approach demonstrated in the project. They all seemed extremely keen. Then comes the culture fit interview. The first and only question they asked was "Describe a situation where a member of a minority group was treated unfairly at your workplace and how you handled that." Having quickly scanned my work experience I said it was extremely diverse working environment in every job and I'm not sure if I can come up with a relevant example. They were clearly disappointed and insisted I think harder. This might be the most awkward interview I've ever had. They were unavailable for feedback after that, silently removing me from their hiring system with the reason "not being prepared for the presentation". Then how come they listened with their mouths opened throughout the presentation? I am still not sure what exactly happened, which is disappointing considering the amount of work I put in.