Wall block won't become a full wall when underneath an upside-down staircase

This seems WAI, as the upside down stairs has no bottom face that covers the whole center + the direction it's connected in.

Typically, when a row of walls is underneath solid blocks they become the full version of it.

But the stairs aren't a full block, especially the side with only half of it on, so I don't really see where the bug is.

If it's an intended feature, then I'll go to the feedback area instead as it's stopping me from finishing my build.

Thank you for responding though! 

I guess the directions where the stair block is shape=straight or inner_left/right, and fills the side of the block, the wall could become a tall connection, but aside from that... :/
(Just to clarify, they don't do that as of now, just that that's a possible behavior that would be consistent with the wall behavior.)

Can confirm in 20w46a

This actually appears to be a duplicate of MC-203378, as this is a more active ticket with further information regarding the problem.