Ok,

Using my bench PSU it was giving 2965rpm one way and 2971rpm the other.

It was also creeping with the inputs shorted out.

I ran the auto zero speed set function which killed most of the creep.

Then adjusted the gain to 305rpm/V

It now gives 3000rpm forwards and backwards.

Did it fix the issue?

No :(

A short video of the Pid screen at 2990rpm and 3000rpm

https://youtu.be/i7GEe7jAoY4