Hi Chris,
I had actually swapped the pins and moved the pull ups, however previously on N+1 I used pull ups to 5V.
To get this working on N+2, I had to change from 5V pull ups to 3V3, though maybe this is to do with my resistor values - which I've kept the same, at 12KOhm.
Would you recommend different resistors?
Thanks,
Richard.