SHeep not regrowing wool, lambs disappearing

I've been trying to breed sheep. In a fenced in area with grass and tall grass. Mating two sheep produces a lamb, but when I leave the chunk the lamb is gone when I return. Also, sheared adults are not eating grass and regrowing wool. Stayed with sheep all night to watch lamb become full grown, sheared all sheep, left chunk, came back, only two sheep left, both shorn and not regrowing wool.