Adaptive Reliable Management Systems Software Engineer interview questions

Gave me three interviews, tech lead was a nice pleasant interviewer, same goes with HR & CEO. I was asked to send over some GitHub repositories which I sent over, they claimed they couldn't see the back-end (which was very clearly labelled) which was slightly concerning. I then had my final interview which went fine, we even had a lot of small talk between, after that they never contacted me again, never messaged me, never picked up my calls, never responded to any emails. It should be common courtesy to simply respond and tell an applicant whom you requested 3 interviews from where they went wrong, or at least tell them that they didn't get the offer. It's concerning and most likely reflects how they deal with clients and their staff