That should be OK then. How long are the I2C wires between the Duet and the Arduino? Can you confirm that you have 3 wires between the two: ground, I2C clock, and I2C data?
This has been solved. The Right-most LED had broken its solder joint so i had to scrape off some of the solder mask to expose some copper to get better contact and after adding more solder to the pin it has resumed working.
The solder joints on those LED's seem to have very little solder connecting them.
Does the Settings General page of DWC recognise the board as a DueX5 and not a DueX2?
What status does M122 return for driver 9?
Have you tried that motor and cable on another output, or a known working motor and cable connected to driver 9?
Nevermind, I have found a way around it, the PCBs had a few components that made it function that way. I removed them and now they will work with the heater outputs as they are.
The GPIO pins have high value (100K) pullup resistors to +5V. You probably need to use a much lower value pullup resistor to +5V to provide enough current to activate your mosfet board.