Yes and it is always the SAME one. GOD only knows why he goes only to that one.The corner that Oli keeps going back to, is that the corner he usually flips over in?
You could try taking a piece of something and just barricading the corner off. A small piece, just so that he's not faced with a 90* angle.
I think for the most part that 2nd stories are considered a no-no, simply because they're more work than they're worth. But if you absolutely have 100% no room available, there might be ways to make it work. Again, you'd be adding a ramp, and more corners for Oli to deal with, but it's possible to cap the corners or at least make it so there's no hard right angles.