It’s a bummer, but not all bad
One could think of it as a practice in dealing with rejection. No need to take it personally. Some things explode, and some things don't. Doesn't mean that the idea was bad. It could have been posted at a weird time, drowned in the trending page, or maybe it was just such a novel idea that no one was really sure how to approach it. I find all sorts of unanswered challenges hiding out on the Recent (New?) tab, even though the Trending tab is the first one to appear when you click on the Challenges link.
It's a bummer. I know it sucks to not get even a single response, so sometimes I try to comb through the challenges and enter ones that are kind of quiet. I often find that the quiet ones force me to think outside of my comfort zone, and being pushed as a writer is nothing but a good thing.