Sulfur cubes visible through ice

The sulfur cube is clearly visible through the block 'ice', even from large distances or thicknesses of the ice that should make the mob impossible to see. This does not happen with 'packed ice' or 'blue ice', so I assume that it is a glitch. Whether or not the cube has a block in it does not seem to matter. I am reporting this here because I could not find a place to report bugs in the Minecraft Preview.