I recently wrote a comment here. While the others rendered correctly, this one didn't:
At first I thought it was my browser, so I fired up another one and it was still the same. I don't think I wrote it wrong because I used the same phrase $$$n - i + 1$$$ in the next sentence and it managed to render correctly (and also here). Did I do something wrong or is it a bug?
I've noticed that that happens when you have a centered latex formula with double dollar symbol, and in the next paragraph you have an inline latex formula. The inline latex formula isn't rendered. Sadly, I don't know a solution for that.