Wither skulls can appear to be in the wrong position

If a block is placed in the same position as a wither skull, the wither skull will appear to move upwards by a block or so. It won't actually move, it's a visual glitch only.

Command to summon wither skull:

summon WitherSkull ~ ~ ~ {direction:[0.0,0.0,0.0],ExplosionPower:0,CustomName:Wither Skull,CustomNameVisible:1}