Well after about 6 months since it happened last, it happened again today.
No idea what caused it, I was using it purely as a controller, so not moving any knobs or switches and hooked up by midi not USB.
I was half way through recording 16 bars when it happened, so I had 8 bars of normal triggering and 8 inverted.
Playing a short plucked sound with no sustain made it really confusing, so at first it just sounded like either the worst midi lag ever or I was having a stroke
Hopefully there's a fix coming soon.