In using commands to fill an area with cut copper upper slabs, I found the data value for this upper slab has not been implemented properly. (This also seems to affect deepslate_brick_slab)

Steps to Reproduce:

1. Create Command Block with Code:

/setblock ~ ~-1 ~ cut_copper_slab 1

       2. Activate Command Block

       3. Notice DV in command is 1, yet slab is still lower variety