Since some snapshots, some blocks with datavalue 7 shows them flat, but when I tryed to do that with Sand, it crashes and don't lets me enter the world, only if I downgrade to 14w10c.
Steps to Reproduce:
There are 2 ways.
1. Do /give @a minecraft:sand 1 7
2. Use /setblock ~ ~ ~ minecraft:sand 7 and copying it in Creative Mode.
Linked issues
duplicates 1
Comments

But there is an item with that value.

No, regular sand has data value 0 and red sand data value 1, nothing else.
There is no sand with data value 7