Having a space within a space in your model will create non-convex surfaces with holes. See this post for an explanation of the issue. It is best practice to avoid non-convex spaces in your model.

You have two options:

• (1) since your zone is entirely internal, you can move the internal space so it aligns with the walls on the bottom and left. You will still maintain the same floor area for the hallway and internal space, they will just be slightly shifted. This could potentially give you incorrect calculations if you have substantial solar gains you want to account for, though it looks like this may be a non-issue as you have no windows on the exterior wall. I would recommend this approach.
• (2) break up the hallway into separate zones. (Do not combine spaces into one thermal zone, as E+ doesn't know about OS:Space, and the end goal is multiple thermal zones)