Thanks, that's fixed it. I must have missed the comment.

-- sort results by area ascending, then volume ascending, then width ascending, then height ascending

you are not doing that in your current solution. note that in ORDER BY , the order in which you write the different sorting criteria matters

In SQL there may be an issue with ordering - I'm pretty sure I have the correct answer but the ordering logic is opaque to me. No matter which ordering logic I choose, it won't accept my answer.