It did happen to me once, during the first competition. I had spent a month working on a level, then got an update that broke my level and ended it all for me. The following release fixed the problem, (after the competition) and that map has worked in every release since. I just quit working on it and haven't bothered with anything substantial since. That's just me though, I was emotionally scarred! If I had a worthwhile idea, I would go with it again with no hesitation. If you do run into an issue, it's usually just a bug, and these guys will work with you to correct it. They're pretty good about these things!