Maybe a little mistake with NLEN?
10.6.4 LEG Controls the legato of the arpeggiator. This setting will affect the note trigs of the track even if the MOD setting is set to OFF. ON will play overlapping notes legato, releasing the old note after the new one. The NLEN setting adjusts the length of the notes when the arpeggiator is activated. If not activated the LEN setting will adjust the length of the notes. OFF will send out a MIDI note off message before the start of each arpeggiated note.