Keep an eye on those air bags. The system will compensate for a leaking air bag by running the compressor so you may not notice it. If the compressor runs too long, it burns out. The air bags become porous and weep air out so you'll never see a hole if you're looking for it. You can spray soapy water on them and see if you have any leaks.
On a positive note, could be as simple as a diagnostic/reset though. Keeping my fingers crossed for you.
It's definitely fun to drive! You have about 360hp under your foot as is sits. Ours ran about a 14.5 at the local drag strip. Not too shabby for that heavy of a vehicle from a dead stop and it handles better than most cars.
Here's a couple of posts from Xoutpost that will help you familiarize yourself with the suspension and the issues they have. If your really interested, I have a white paper from BMW that explains the whole system in great detail.
https://xoutpost.com/bmw-sav-forums/...-question.html
https://xoutpost.com/bmw-sav-forums/...libration.html
https://xoutpost.com/bmw-sav-forums/...-please-2.html
Lastly, if you find that the air suspension is too costly to fix, ECS Tuning has a conversion kit. You have to code out the air suspension though...
https://www.ecstuning.com/News/BMW_E...Conversion_Kit