sheep assassin unknown

when i went to go breed my sheep i found out something a bit odd. but first let me say i have been breeding each floor of sheep simultaneously meaning when there are 13 on lv1 there are 13 on lv 16 and everything in between. so i was a little surprised to find i was missing sheep today so in my mind that leaves three possibilities some glitch i have never heard of, mobs spawning in a well lit room killing sheep and De-spawning or perhaps in minecraft mobs De-spawn now despite patch info saying otherwise. however i was informed it was far more likely some1 had broken into my farm replaced the broken blocks and proceeded to kill the sheep. i had not considered that possibility because my farm is far from spawn and the few people who do know about it are trusted or donators. i am posting with the hope someone more knowledgeable than me knows what is going on and perhaps how to fix the problem assuming its not some player and also to vent a bit of frustration probably. the grief hypothesis makes sense but idk why any1 would do it that way.

I swear to whatever god you believe in I did not do that. Js