DDJ400 not being recognised as device by mac

My DDJ400 suddenly stopped working for mac only. It does not show up as a USB device at all on the mac system report. I've had it checked out by a local store and they assure me the boards are all fine. I've even seen it work perfectly on their windows machine with the large USB (A?) port. 

However it does not work on my mac or any other mac I've tried - all of which require converter from USB-C.

I've tried different macs, different cables, powering separately to data with a split USB cable and it never shows up as a device on the mac. I've used another DDJ400 in the same setup and it works fine.

Any ideas what to do now?