Can't create custom opening (grayed out)

[cocoloco]

Hi! as the title says, I regularly need to use custom openings directly in elevation. But that setting is not available (is grayed out) also in floor plan...?

but it is grayed out! I intended to do hole in the slab/box for fireplace or niches in the wall (very simple) 

Any solution to it or it is not suppose to work in interior elevation for some reason? 

[Barry Kelly]

Your image shows that the irregular shaped polygon input method is active.

You just need to draw the shape.

Or do I misunderstand what you want?

Barry.