For context, this role was unpaid. I was given a take home assignment that took me a few hours. After submitting, I was invited to an interview. My interviewer did not show up. After 15 minutes I emailed the only person I had come in contact with throughout the entire recruiting process. After more than 30 minutes (long after the designated interview period had ended), they replied telling me 1) they weren't the person who was supposed to interview me 2) "here is the email of the actual interviewer, reach out to them" and left me to it, no apology. I didn't end up doing so because at that point it was not worth pursuing considering the role was basically a volunteer position and I had already spent hours on the take home assignment. They never ended up following up with me or apologizing either.
TLDR: Did some unpaid work, interviewer didn't show up, and then I had to HR myself through the process
