Azhy

I have a 2012 E550 4matic. My front end used to drop very rarely and would be over night. Now it happens every time I am not driving the car. The front would sit as low as it can go (rear ones are fine). When I turn on the car it would go back up to normal level (with the message "vehicle rising"), but sometimes it would take a good while to get to normal height. The button that increases vehicle height also works fine. Driving it also seems fine so far.

What is my issue here? Any help would be appreciated,

Thanks.