My first thought was wouldnt a hole in the exhaust that affects the 02 lamda sensor throw up a code for that, not a misfire on a specific cylinder.
But on further thought maybe the ECU is trying to bring the exhaust 02 levels ( an indicator that the engine is running efficiently) back to normal by changing engine settings, for instance by changing the fuel/air mixture . In which case the first reading that causes a fault code may be when one of the cylinders starts to misfire slightly because its getting the wrong fuel/air mix. But the changes may mean the 02 sensor will be getting the correct levels, so doesnt show its own fault code.
May be of no help, and sorry if I am stating the obvious