Hopper Minecarts are still randomly disappearing even though a search reports the problem corrected.

My hopper minecarts are randomly disappearing.  Usually happens when I have travelled away from the base and I return to find my wool farm broken.  Sheep are always gone.  Sometimes cooked meat is present in collection chest.  Other times I have found the cart only in the chest but hopper is missing. But, everything might have disappeared as well.  Tried naming sheep to see if that helped.  Answer is no.