Hi, I have found a Unintended Walled-off Unit (or UwU for short if you'll allow me) just before going out of the White House on the corner of West Executive Ave NW and South Lawn Road. Trying to find a shortcut I fond myself locked away in a small subsection of the perimeter wall, unable to get out. Fortunately, I remembered that fast travel was a thing and all was well. But if a map designer comes through here : you missed something.
I have linked an imgur album with more details : UwU