Mud Brick Stairs, Slabs, and Walls variant aren't grouped together to their respective block group in the creative tab menu

The mud brick stairs, slabs, and walls variant aren't grouped in their respective block group in the creative tab menu.

This is how it should:
Mud brick stairs are grouped together with the stairs group.
Mud brick slabs are grouped together with the slabs group.
Mud brick walls are grouped together with the walls group.