It would be interesting to get magnet viewing film in a large enough sheet or several sheets and see what the magnetic field lines look like along the strip

That is the point where you can collect energy

The way it stayed on the table makes me think there must be something under it. You mentioned the rebar, maybe that one is the closest one? Or maybe some fragment of metal is stuck inside the table? I'm not rly seeing any other way this could be happening

might have something to do with the multiple interfering magnetic fields

what happens when no other magnets are present and you try to place the ball on that spot?