I have a village that is 3 chunks wide and 3 chunks long in a desert biome. I am moving my villagers on mine carts around my village and around my base that is next to my personally made village. My villagers are sitting in mine carts that are on the ground and not resting on the tracks, they are in separate single file lines for each profession/career, waiting for the next set of tracks to be placed on the ground. I just finished a headcount with 43 villagers that came from my 3x3 chunk village. I went to my storage area for building materials and when I came back to my villagers all lined up I saw that 10 villagers ( the farmers and fishermen) and their respective minecarts have vanished. My game is set to peaceful survival. This is a problems since there is no reason why they would be missing.

sorry no pics of the event.