Hope you have solved your problem but if you haven't, this may help.
My 2007 RRS had a similar situation. The front left would settle overnight but sometimes it wouldn't. After a few days of non-use the car would settle down to the stops on all four corners, but sometimes it wouldn't. The orange suspension light would always come on after about an hour of driving.
My local indie tech hooked up his Autologic and noted the rear left shock was constantly moving up and down through a 1mm range so we figured it was leaking and replaced it. Nope still settled. The next suspects were that the cross-over valves were leaking internally so we replaced both--front and rear. Nope still settled. All these parts were sourced from Landrover OZ at exorbitant prices.
Getting a little weary of this expensive suck-it-and-see method of diagnosing the problem, I asked the tech if there was a way we could test the entire system in one go. After a few minutes thought he suggested we put an oil based fluorescent die through the system, drive the car around for a few days and see what happened.
Well, that did the trick. Minor leaks were detected in the two right side shocks, nothing in the left rear shock or cross-over valves as these had been replaced and a moderate leak in the front left shock (the corner that always dropped first).
It also showed up a leaking head gasket in the just-out-of-warranty replacement AMK compressor (replaced under a recall).
Fortunately there is an overhaul kit available for the AMK so a new compressor wasn't necessary.
The three replacement shocks, the AMK kit and replacement desiccant (decided to do that too) were all sourced out of the UK at really good prices compared to local. Just had to wait a week or so for delivery.
Now everything is perfect. No warning light, no traffic light dance, all good.
Next problem? The anti-theft alarm sounding off without any human assistance. I suspect it's the bonnet latch.