Dreaded "inactive leveling suspension" message
 

UPDATE: 5/4/16

Decided to go with:

https://www.ecstuning.com/BMW-E53-X5...ngs/ES2770534/

While it's about $150 more than Suplex spring and OEM pads sourced separately, It does come with BMW springs and ECS is responsible for kit fit as they've assembled it.
Suplex is more than likely direct fit and quality brand but I can't return it if something is wrong.

As many of you here know it's pointless to go into details as cause could be very simple and cheap or not simple and expensive.
I'm not going to waste my time chasing the issue as I made up my mind to switch to conventional rear coil springs.
I have 104k miles on it at the moment so I'm not going to change any other components as they're still in very good shape.
I've decided to go with German made Suplex 06204 coil springs as they're very high quality and basicaly an OEM replacement for 3.0 with optional rear coil springs.
SUPLEX 06204 Rear Coil Spring for BMW X5 | eBay.
With OEM upper and lower spring pads, I'll be under $200.
My understanding that 3.0 coil springs are direct fit and will keep the stock height. I'm not interested in all those kits lowering the the ride as they can get expensive in a hurry with no clear picture what exactly you end up with when it comes to fitment and ride.
I'll replace them myself and I'll deal with message later as I haven't decided yet which way to go to get rid of it.
I'll post update when I finish the project.

I believe you can just code it off if you go to coil spring.

I look forward to seeing the outcome of this modification on a 4.6is.

That's the plan. I do have fairly capable AutoEnginuity scan tool but this is in the GT1 league. More than likely I'll use reputable indy.