I suspect that the left rear airspring has a bad leak and the vehicle is pivoting on the left front and right rear making the right front high.

Have a look on the 4x4 info screen, see if the line under any of the wheels is flashing red.

It could be a height sensor that’s gone out of range and is confusing the car.

David. 2002 4.6 Vogue SE - Alveston Red with Lightstone Leather
2007 Range Rover Supercharged in Java Black with Ivory Leather
2012 Range Rover 5.0 SC Autobiography in Indus Silver with Jet/Ivory Interior
2012 Range Rover 4.4 TDV8 Autobiography in Baltic Blue with Sand Interior

Hi David and Graeme, thanks for your input, I don't think it is an airbag, both bags still have air in them albeit not enough to lift the vehicle, there doesn't seem to be a connection between the front and rear axle, the front goes up and down (but does want to be in extended mode) the rear doesn't move at all. All four sensors are pointing the right way, no obvious loose wires or such, battery has 12.7V compressor switches off when the tank is full, drilled a hole in the sintered filter, tried a battery disconnect, jacked up one side but nothing seems to get the rear to lift, almost like a physical blockage is preventing it from moving.
No red lines on the 4x4 screen but it does show the rear axle height being much lower than the front there is no air escaping so now I am about as confused as the fattie..
Any suggestions most welcome.
Anyone wants to get rid of an IDII can you let me know, is does look like I need one as my more mainstream code reader is at the end of it's knowledge.

One of ours did the exact same thing a short while ago, turned out to be a failed rear height sensor. Not saying that's definitely your problem, but it was ours. Hope you get sorted. Drives:
2010 FFRR TdV8 Vogue - Stornoway Grey
2010 FFRR TdV8 Vogue SE - Zermatt Silver
1998 BMW E36 M3 GTII

If you are getting full air pressure at the tank and the back will not lift at all it sounds like the air is not being allowed through the rear valve block, as in other posts, possibly caused by a dodgy height sensor?. On the rear valve block, slacken the tubing, find out if air is getting to the valve block and if any air is coming out of the two tubes from the block valve ( distributor valve ) Have a look at the wiring.
Another common issue is after being in extended mode, sometimes the system gets 'confused' - Try the steering angle sensor reset. Stationary with engine running and car in park with hand brake off, centre the steering wheel, go to full left lock, hold, then to full right lock hold, then back to centre, repeat this procedure again. This may not help but it has worked on my 2006 when its thrown a wobbly. Hope this helps or at least rules out certain faults.

I have jacked the car up at the rear and I now have a faulty sensor reading on the 4x4 screen for the N/S height sensor, this might well be the cause of the confused fattie.. I will see if I can find some info about testing the sensor on the bench to verify it's failing but I will still check the rear valve block for it's functioning. thanks for all the help so far.

Will

I just bought an ID II from BAS, that will be step one in the process

Well, installed the new height sensor, noticed a crack in a wheel, bought Ipad for use with IID, does not work, too old, cannot update IOS. Don't despair, download Apple app onto laptop and setup and update, Ah, app does not work on laptop, try Google apps, same problem, load app on OH Ipad, well at least that bit worked, Sadly Ipad does not have a sim card so won't work in the garage, no problem, take car out of garage, nearly drive into the kitchen and connection works. Plug in IID, ignition on, connect Ipad wirelessly, it works. Register IID to vehicle, login to app, nah, I don't think so, the right hand side of the secreen can't login because the email and login are already taken, the left hand side of the screen doesn't like what it sees and tries to login, no idea what it wants but I have had enough of it, after 3 hours trying to conect to the damn thing I need some food, a long walk and to calm down before I shoot something.
Rant over (I hope)

Finally done it, registered the IID in offline mode, that has worked.
Now for the height configuration, not sure I am ready to attempt that as yet...

So it was the height sensor? 2012 Range Rover HSE | 2011 Range Rover Autobiography | 2010 Range Rover Sport Supercharged
2020 Tesla Model 3 Performance, 2013 Mercedes-Benz G550, 2008 Ferrari F430, 2007 Volkswagen Touareg V10 TDI

Yes it was, after installing the new sensor everything went back to normal.
Will