Hmmmmm....Range Rovers don't really like dangler lifts...
What can happen is as the axles drop, this moves the height sensors to a position that is rarely used and can drag crap over the internal wiper....
The height sensor is basically a wound coil and a wiper arm...as the wiper arm moves over the coil, the resistance the wiper picks up changes....if the wiper moves to a point on the coil that is not normally used and is dirty (like when the axles drop) it can interupt the height signal....causing issues.
If the rear rises and the front struggles....the system is designed to raise the rear first, then the front, then rear then front again, this is to stop dazzling the oncoming traffic, if the compressor is tired, it will not have enough ummph to fill the tank to raise the rear, but as the tank level drops, the compressor then struggles to fill the tank and raise the front...
Try the Wammers compressor check first - No Air Pressure, No EAS!
If that checks out....it could be a split bag on the front....Dangler Lifts stretch the Air Bag to full extents and this can potentially reveal splits in the bag and allow the to open!
EDIT: Your location is a bit further away from who I thought could help, he is further south near Poiters.....still give Datatek a PM, he can supply the EAS Diagnostic cable and Software for £12.50 +postage or whatever that is in that funny foreighn currency you guys use