SNOW GOLEM DESPAWN

Device:samsung galaxy tab 4

I create a snow golem for snow farm, but when I leave my snow golem and have an adventure, the snow dolem disappear where I placed it. There are two iron golems to protect my home and proper lightings, I use slab to enclose my iron golem to prevent soffucation, but the only remains of my snowgolem is the 1 snow layer

Sorry for bad english