This legit just happened again with the new story I'm working on, so I guess the moral of the story is to trust the process and your own creative head? You'll have a eureka phenomenon even when you're feeling really stuck on a part of the process as long as you don't just give it up altogether (this doesn't mean to not take a break, breaks are good.)
But I was stressing about the climax which was just feeling kind of flat and meh, and then a new ending came to me randomly. it did mean have to re-plot the end chapters, but in the end, I think it's a whole lot better than it was before.