Do this in survival. So you can transport a villager with a boat, by villager riding in the rear and you driving in the front. But occasionnally when you get a villager in a boat through a diagnal block, it glitches out and sends the villager back to where it came from, visually. You cannot interact with that "villager". The actual villager is somewhere else in the world invisible. A re-log can fix this issue, however, when you have a villager on the lose, everything is scary. It also happens when you break the boat, it sometimes teleports back to where it came from and after a minute it would come back. When the "villager" is glitching out, it would always face to one side downwards, and you know something is wrong. Trading also makes this problem appear, but the villager just walks through the diagnal blocks a couple times and then go back in. It's very annoying and scary, and should be patched immediately.