360 2nd to 3rd not happening when car warmed up

Car has been sat for a while - although the engine was run up each week.

After the car has got all her temps to normal (about 20-30mins) if I end up in 2nd gear and attempt to go to 3rd the display sort stays stuck on 2 and then goes N and then the engine is a bit like it's torque limited.
Nothing is happening until a shutdown and restart.

Errors
- P1760 (nothing obviously wrong with the bake lights)
- P1770

Have checked the settings, all is good.
if very quickly after it happens I instruct a shift to 3rd using the Leo, it will fail,
Have tried a 'relearn' with the gearbox hot - just in case , all gears were selected it all went well.


My guesses are...
1. Position sensor.
2. Moisture/air in one of the actuators.

Open to suggestions.

 

It's back to behaving itself, for now at least

I'll invest some time to
- bleed the system
- observe the position sensor values using the Leo.