In my first attempt placing furniture at the Sanctuary (where the Last Minuteman and his friends live) the chair that the old lady asked for was placed on the second floor. I was on the first floor but it was possible to put the chair one floor above, even though there is no actual floor there.

When I started playing the day after I saw through the roof that the old lady is sitting in the chair. The problem is that there is no way to enter that floor. Even if I build some stairs there is no entrance. It is a graphic bug. I guess she will be stuck for the rest of the game ...

I am afraid this will affect the story/gameplay and hope there is someone with a solution.