animals get through fences

this has never happened to me before until now.. just last night i built a barn for my animals and some storage and i currently have cows and sheep in 2 different areas.. i am also playing on a server.. the animals r being held by fences and when i logged in this morning 3 sheep were outside of where they should of been and a cow.. and i dug around looking and i read about fences not counting as a full block so they could glitch through?.. my problem with that is before moving them to the barn they were in fences and i had no problems until now.. also it wasn't like they were right outside the fence on the other side.. they were 3-5 blocks away from the fence.. something isn't right here.. i have included a picture of the setup which is almost identical on the other side.. only difference is when it first happened i extended the pen for the sheep out a couple blocks connecting it to the front of the barn giving them more room thinking it would help but it didn't.. it seems to happen when i log out and log back in no matter the time difference because it happened when i logged out and logged right back in right away as well.. i hope this gets addressed so each time i log in i don't have to chase down animals