Left-sloping Inverted Walls have no stability

Game mode: Private | Singleplayer
Problem: Bug | Misc

Tested up to T2 of “Left-sloping Inverted Walls” and they do not have the ability to have anything placed upon them. Not sure if it’s just that it’s not getting stability or where the issue lies.

Right-sloping will however fill the gap, but in a backwards position and can have things connected to it.(wall above or connecting roof tile etc)