IXL Learning Product Design interview questions

Applied online for the product designer job and got an invitation for a phone interview. Pretty straightforward process. The interview questions were fairly general. There was a quiz at the end of the interview which was tricky but not difficult. Heard back two weeks later saying they didn't want to continue.

I applied online through my university and received an email requesting a phone screen about a week later. They were looking for a history curriculum developer, and I had a lot of experience in education and history, so no problems there. The phone screen was like what many others described. They used a brainteaser, slightly modified because I think they know people are hearing about the jelly bean one (this one was about treasure in 3 treasure chests). The brain teaser was a bit tacky and weird-it was hard to visualize/understand the construct of the question. Once I got it, I got it, but it was not well explained and the interviewer was not very cognizant of this. Around the end, when the candidate asks questions, I asked about what kind of challenges the history curriculum was facing. The interviewer said that scoring and random generation were issues with this particular content. More on this below. After the interview, I was emailed a work assignment, like others have noted. It was very in-depth and quite lengthy. I was already concerned given what I had read about other reviews on Glassdoor about doing a lot of work on an assignment and then getting no response/rejection back. An additional concern was that the questions specifically dealt with the random generation and scoring issues discussed in the interview. Basically, the assignment appeared to be free work for them to resolve an issue they were having right now. They gave me a week to complete this. I decided to decline proceeding further in the process. The HR coordinator emailed me back with a brief thank you message.