Were they previously making sounds?
No. The behaviour is consistent. Sometimes they are making a VERY faint sound, but mostly none at all.
Are you running through a daw or other midi device?
Yes. Either Logic Pro X or Ableton 10 and being controlled by an NI S88mkII and Codeknobs software. But again, most of the sounds seem fine. It's about one third where there is no sound.
Are you controlling it with the attatched keyboard or is it a desktop module?
Desktop unit. All connections and settings have been verified several times. Not my first rodeo. Not trying to be a smartass, but I've been doing this for a while which is why this is baffling me.
Is it possibly set to be synced to external clock yet you’re not sending it one, therefore rendering all arpegiator/sequencer patches silent?
Hmmmmm, I don't THINK so? Don't all the arp/seq patches light up their prospective indicators on the front of the unit when that is the patches purpose?