MapClouds (hex color code) rare cloud is broken by itself and will not allow the planet to load on the map when this line is by itself. Specifically, the actual ground of the planet loads fine and is solid, but there are no gates above the player's house. Dungeons will also look as if the player never entered the medium, yet my sprite is no longer an orb.

It works okay when paired with another map line of a different sort, specifically, one of the MapWater and/or MapGround lines, but I suspect that, if there was a delay in loading the map lines (let's say, there's lag in a multiplayer session) and rare cloud loaded before the other line, then it would glitch out the game. None of the other map lines have this problem.