Arp not always working and timing is messy

[FastGraph]

Most of the time you have to press the arp button a couple of times before it actually start arpeggiating the sound.
Button lights up but you just get a single hit from the notes you play.
I'm sending one note from a Pyramid sequencer that's also sending clock and some bars the arp (when it's working) is nicely synced but after a few bar it seems to skip the firs step...