very very weird removed start block...

this bug will be weird, i use this command to give a written book - 

/give @p written_book{pages:['{"text":"Welcome to the Guide of Tameablest mobs ever\\n====================\\nthese mobs can actually spawn everywhere, creepers, zombies and spiders in a dungeon and a pig that spawns in plains, in updates it will be added new guide versions and new mobs to the game."}','{"text":"How about them from Taming in different item\\n=====================\\nyou need a source of item killing by creepers, zombies and spiders. from dropping these items, these mobs have green eyes, they just friendly but tameable, and source of food type of tameable mob, for the mod :)"}','{"text":"How to tame a mobs?\\n===================\\ntame a mobs, you need for killing a mobs by dropping the items or cropping a food, tameable pigs, spiders, zombies and creeper while be not friends with other friend attacks you."}','{"text":"How you get the items from taming the mobs?\\n===================\\nthe items was killing by spiders, creepers and zombies or get the crops by carrots, only you can tame these creatures, this is a guide as a tameable mobs with tameable items by killing mobs or get the crops, it will help :)"}','{"text":"Tameable Creeper\\n=================\\nHP: 20\\nAttack: 5\\nTaming by: Gunpowder\\nSpawns: Dungeons\\nDescription:\\nTameable Creeper is a friendly Creeper, this creeper is a tameable with gunpowder, for killing by original creepers."}','{"text":"Tameable Zombie\\n=================\\nHP: 20\\nAttack: 5\\nTaming by: Rotten Flesh\\nSpawns: Dungeons\\nDescription:\\nTameable Zombie is a friendly Zombie, this zombie is a tameable with rotten flesh, for killing by original zombies."}','{"text":"Tameable Spider\\n=================\\nHP: 16\\nAttack: 4\\nTaming by: Spider Eyes, String\\nSpawns: Dungeons\\nDescription:\\nTameable Spider is a friendly Spider, this spider is a tameable with spider eyes, strings, for killing by original spiders."}','{"text":"Tameable Pig\\n=================\\nHP: 10\\nAttack: 4\\nTaming by: Pig\'s Foods\\nSpawns: Plains\\nDescription:\\nTameable Pig is a Pig that uses a taming, this pig is a tameable with food for pigs, for getting by food like potatoes, carrots or beetroots."}'],title:"Tameable Guide",author:TameableMobs,display:{Lore:["this guide is a from tameable mobs: remastered. only these mobs only as pigs, creepers, zombies and spiders"]}}, but it removed to element?, it was weird bug to the mcreator, but i was screw up to my mind was broken, this was a bug... when i have save the element, i go to the procedure, it was very empty, but how it removed the start block?