Arpeggio Sequencer Behaves Differently When Synced to DAW

I finally got my OP-1 synced to the clock in Pro Tools but the Arpeggio sequencer behaves strangely when connected. It plays the first chord as an arpeggio and then just repeats the top note. That is to say, it doesn’t keep on sequencing all the notes. As soon as I unplug the USB, it goes back to normal.

My goal is to play the arp sequencer and have it line up to the grid in Pro Tools. Seems like I can only do one or the other. Any solutions?

Might be a MIDI loop: your DAW outputs clock, the OP1 sends the arp’ed notes back to the DAW which "thru"s them back to the OP1…