2014 Mini cooper petol, FG14EOC WMWXM52000T943451

Came in for service & MOT, TPM warning light on, so tried adjusting tyres pressures and carrying out reset no luck, checked global scan for faults showed relevant faults in ABS system. Cleared faults and tried reset which appeared to be working on road test as relearn % rose steadily to 49% after about 3 miles, then remained at 49 % until around 8 miles when TPM light popped on showing a fault.

Fault codes logged (Delphi)
48069E - tyre pressure control ; wheel Identification at start up, no calibration possible
4806B8 tyre pressure control; wheel electronics, no valid signal front left

Swapped front wheel left to right, repeated reset an road test, same, stuck at 49% light re appeared same fault codes but now 'Right' front rather that left front. Concluded that it must be a fault with tyre pressure sensor so replaced with new one from BMW.

Reset & road test, same rose to 49%, 8 miles light popped on, bugger ! This time fault codes for 'BOTH' front wheels !
Moved front wheel to rear, repeated, fault code now Left front & left rear ! so almost seams random to me.

This has tyre pressure sensor in each wheel and based on the little info I have the 'reset' is to re learn tyre position after wheel change rather that to calibrate system to rolling circumference of tyre.

No function on Delphi to enter ID of new wheel sensors, of live data showing such info.

Advice on general system operation and possible cause welcome !

Thanks Aidan