Invisible Wall causing edge of deck to disappear

[PitMan71]

In the attached I have a stair going down from a covered grill deck, part of the stair is under the cover too. I want a flat ceiling in both spaces. When I add an invisible wall on the back edge where it intersects the corner of the deck it cause part of the deck under the bordering railing to vanish. Any idea how I can fix this condition or if there is a better way to get the flat ceiling over the stair. I can usually figure things out, but this is stumping me.

Bryan Lake Addition.plan.zip

[robdyck]

Try this

 

[PitMan71]

It didn't work. :/

 

It wanted to put a post on both sides of the stair. Little quirks like this can slow you down. ugg.

Edited February 5 by PitMan71

[PitMan71]

I figured out what to do. Just change that space to a deck room and delete the deck boards and joists under the flooring section on the structure panel. TMYK.