I was invited to an interview with a marketing or content manager -- this was almost a year ago now, so I can't remember all of the details.
After that interview, they moved me on to the assignment phase. Like a newb, I did the assignment, and honestly, I know I'm good because my website ranks on page one for my category, I have tons of repeat clients, and I've earned them a lot of money.
Possibly they used the assignment to optimize their competitor comparison page and display ads.
Weeks passed after the assignment and I had to follow up. They said they were not moving forward and did not give me feedback when asked.
Occasionally, I would check LinkedIn to see who they hired. They kept that Conversion Copywriter job open for a very long time, possibly putting others like me through the paces, and ultimately never hired anyone with that title -- at least, no one on LinkedIn.
Were they just getting free ideas? Maybe. Or, they just didn't really know what a conversion copywriter is and had to learn over several months.
If I take the time to do an assignment, a company should take the time to give feedback.