In the small tenement (the 4 storey ones with a lift and a gap in the stairs at ground level) I have been trapped in the same by two different routes. One or two months ago I went up the lift and down the stairs. I fell through the gap in the stairs and ended up in a basement where i was stuck, hemmed in by invisible walls. Today I ran passed the lift entrance and round the corner. A zombie came in and I swung an axe a couple of times then glitched through the wall and was trapped there. I could walk around a little but when I did I fell through below the floor level as last time and was trapped there as before.