4.8is SLS strange operating mode after calibration attempt

[Beniki]

Hi all,

I apologise in advance for posting yet another SLS thread. I also apologise for the long post, however I feel that some background is useful. The key behaviour is described at the end, so you can skip the background if desired.

I have a 2004 4.8is and as per all of these models I have had some interesting experiences with the selflevel suspension.
My experience started about 2 months back, when i started having SLS inactive messages popping up. Long story short, the fault was found to be caused by a faulty alternator, which was causing all sorts of errors on most body systems.
I also noted throughout this experience that the FL corner of the car would sag when the SLS was inactive, which lead me to leak test and identify pin leaks from the FL air spring.
After the alternator was replaced, the car reported no further errors for nearly a month. However, to prevent undue strain on the pump and sls system, the leaky air spring was replaced on Thursday with an Arnott unit.

I asked the workshop to perform a ride height calibration after the spring was installed, as I noted that the car never rode truly level. This was done using a SnapOn OBD scanner.
When I collected the car, I noted that the ride was very high on the rear. This levelled out as I drove home, however at the same time the car reported the SLS inactive error, accompanied by an orange TPMS light.

The workshop directed me to another BMW specialist who had a DIS scanner, as they thought perhaps the SnapOn system did not perform the calibration correctly. DIS showed an EHC 80 code for an implausible measurement from the FR corner. We attempted numerous times to calibrate the level, however eventually we did a diagnostic on the ride height sensors, which showed no change in reading from the FR corner. This test was repeated with the sensor actuator arm removed and moved manually, with no positive outcome.

This is where the odd behaviour comes in:
I had ordered a replacement sensor, thinking that this would remedy the issue, however upon leaving the shop the SLS inactive message disappeared and the car is now riding level. However, the operation of the raising/lowering system is now quite odd.
When the lower button is depressed, the lower LED flashes whilst the middle LED remains lit and the system lowers the car until I press the raise button. The car then will stop at this level and the middle led remain lit. The same is true for raising. I am not sure if the car remains at this height whilst driving - I do not wish to test it as I am cautious about placing the car in an odd ride height in case the SLS inactive message reappears.
This is unlike the system's previous behaviour, which simply raises or lowers to the preset heights.
Is the system stuck in some sort of odd mode? Or is this indicative of something more sinister? Any ideas are very much appreciated.
I have ordered a INPA OBD cable, which will allow me to diagnose the system myself, but in the meantime I am at the mercy of workshops.