Paint on tile is bugged

So one of my tiles on my landscape is acting weird. See image… it’s only some of my materials that it happens with but only on that tile. So the bugged tile is the one on the right and I’ve painted with several materials from left to right but e.g. the snow shows up as the dirt material on the right side even though it’s suppose to be snow like on the left side. Also the it blends in straight lines on the right side. Anyone knows why and how to fix it?

Anyone have a clue?

There must be someone who knows something… help