Arturia Keystep pro -- Record an arpeggio into the sequencer:

 To record an arpeggio into the sequencer:

Select a track (2,3 or 4) and set it to Arpeggio mode.

 

Select an empty pattern in this track.

 

Set Mode to Poly ('Shift'+ Poly).

 

Deselect overdub so it's off (to get a better idea of what's happening).

 

Start the Arpeggiator (press Play).

 

Press record, hold down a chord to start an arpeggio.

Now, simply press the sequencer button on the same track to activate the sequencer and start playing back the recorded arp.

All 'Shift' edit options are now available to further edit the sequence.