Behringer NX series crazy limiter distortion vs inuke

Ok so I have found a big difference in distortion on the limiters when comparing the inukes to the nx series. With a long hold/release limiter setting there was no audible distortion in the inukes, it just capped the volume but with the nx6000dsp it distorts like crazy. This seams to be regardless of the threshold and the input signal level. I have Tested on two amps with the same result and the distortion gets worse as you turn down the threshold or smash it harder.

Its as though the very long (2sec hold + 2sec release) settings are simply not working and the limiters are just sharply clipping (no hold or release).

The Inukes worked great with long settings on the limiter as you could hit the limiters really hard and the speakers would sound the same, and not get any louder. If this is just how it is I would trade all my NX for Inukes if I could...

Am I missing something here? Has anyone else come across this?