Sometimes nothing will convince the other person in a debate
There are some people who are so invested in an idea that they will deny or explain away anything contrary to that belief. This is often characterized by impossibly high standards for evidence to the contrary, and extraordinarily low standards for evidence, as long as it supports that idea. They may even casually fling out mutually exclusive explanations, hoping that something will "stick" and support their pre-determined truth. When you encounter this, it's often best to change the subject or exit the conversation altogether.
Interestingly, you can find this same attitude in some subset of people on both sides of contentious debates. Atheists and religionists, for example. My wife was once engaged by someone who asserted the Bible was false - because "everybody agrees that the Garden of Eden was in [such and such a place], and apples don't grow there." When it was pointed out to the woman that the Bible never said "the fruit" was an apple, she said that wasn't actually the point. And if the point was merely the idea that the Bible is false, and not that it was false because [reason X], then that makes perfect sense.
(Preemptively - I'm not interested in defending the truth of the Bible; I'm just pointing out that the above specifically was a terrible argument against it.)
This is not to say that everyone who resists a claim of evidence is automatically logic-free and irrational; sometimes even a well-documented fact, in isolation, is not enough to counterbalance a collected weight of evidence on a murky topic with apparently contradictory information, about which people can reasonably disagree (think questions about macroeconomic systems, for example). But don't imagine there's anything useful to say to debate someone who's made it obvious they aren't interested in being reasonable.