Coble Stairs disappear after loading up game

I loaded up my world and where coblestone stairs were, now is just a dark shadow. I can walk through it. I can place block in the space and the shadows fix themselves.

I created a new creative world. Placed all types of the stairs. Quit the game, and then loaded it back up. Noticed the default wooden stairs and coblestone stairs act the same. Everything else works find (for stairs).