This issue can be recreated by using the elytra to fly straight upwards (with firework rockets) (over any biome or world type) in the versions 17w48a - 18w08b after issue is recreated there is a screen that says "Connection Lost" then below that it says "Invalid move player packet received" then below that it says "Back to server list" (by the way) I was playing in a singleplayer world and did not have LAN on.