Phone interview with HR. Then with Architect. Then with 3 senior software engineers. And finally lunch interview with a few managers

This interview started off incredibly promising. Both the recruiter I talked to and the engineer who conducted my interview left good impressions on me. After my interview with the lead engineer, I was asked to do a take-home project. I was tasked with creating an API that would keep track of and update tickets for an IT department, with certain information included for each user. It was a simple enough assignment, but still something that takes considerably more time than your typical algorithm assessment via Hackerrank or CodeSignal. After completing the project, I sent my GitHub link, and waited. And waited. And I’m still waiting. It’s been 3 weeks now. I’ve tried calling, I’ve tried emailing, and I’ve gotten nothing in response. Not even an automated email. I’ve written bad reviews for interviews before, but this might be the worst I’ve ever experienced. The level of a lack of professionalism and disrespect is quite frankly astounding. They couldn't even send an email, or make a 5 minute phone call to say that they've gone with another candidate?