I asked Medium about the failed Boost on this piece, and the (prompt and courteous) reply was 'Nah, it's all good. No changes to the algorithm or anything. Maybe it will pick up, but otherwise your story just died a natural death'.

Which remains puzzling, as it was one of my best, I think.

I'm still working on the theory that the 'Fire' topic tag may have caused it to be sent to people interested in Amazon media products, which was why it was getting the thumbs down. I've now removed that, and will update the story if it makes any difference.