PolyAI Software Engineer interview questions

Applied on Linkedin, got invited to a recruiter screen,had a good converstation with the recruiter, they mentioend a take home coding task next and described it as "straightforward", it was actually 4 questions, 2 easy questions, 1 medium and 1 hard all within 60 minutes. I did them all and had 2/6 test cases failing on the hard question, got an email after giving me an 86% score. That question specifically seemed to be intentionally setup to be frustrating as the environment errored when any debug print statements were added (only on that question) and a video animation played on half the screen on every test run. The recruiter then said they reviewed my submission for the coding task and asked for my availability for the next interview, which I sent for the following week. I hadn't received an update by mid-week so I updated my availability and sent the recruiter an email. The recruiter then sent me a generic rejection letter. I'm not too concerned with the exercise being difficult, but more disappointed that the recruiter (or the team) would invite me to an interview and then change their mind, The recruiter also did not send the task until I emailed to ask about it.