If there’s a tile within a tilemap that’s out of range of its tilesource then the tilemap doesn’t display at all in the scene editor. I’d reduced the size of my sprite sheet and unknowingly still had tiles in my levels that had been cropped out of the sprite sheet.
@Ragnar_Svensson and @Ragnar_Dahlen: Is this case handled in the new editor?
If you use Tiled to edit your tilemaps and save Defold tilemap data this can be avoided.