Pinterest Product Manager Apprentice interview questions

I sent in my resume, cover letter, and answers to application questions. A few weeks later I received an email that said “you have an interview coming up with Pinterest…YES!” There was a challenge attached. Immediately there was lots of buzz on social media platforms among those of us who received the email. Were we all going to be interviewed? Was the challenge an elimination phase? It was unclear. I did the challenge, submitted it, and a few weeks later…got the form letter rejection email. No interview. I understand a program that size can’t give feedback, but they should reword the first email so it doesn’t sound like a guarantee of an actual interview.