Manual states this: -4 thresh, 20:1 ratio, 5ms attack, 200ms release (should cap at -6)
Also, is the channels are "linked" then so is the limiter.
But, this doesn't explain your waveform, and now your results do look pretty weird. Except for very, very fast attack transients, you shouldn't ever see anything above -6. Weird. Is it possible the limiter was only engaged on chan 1? Is that even possible, that could explain it. The asymetical wave is from the horns, but only chan 1 was limited. Otherwise, that truely is weird?