There are many things that can cause it but odds are very high the brake light lead became "high" (Or Hot, depends on the technician you are talking to) how can this happen? (And note there is one other possibility)
1: Some drivers were taught to drive with left foot resting on brake pedal (I was taught to drive a stick, we need the left foot for other things). If you hit a bump you might "tap" the pedal activating the brake lights and putting the CC into Standby.
2: Weak break return spring doing same thing as foot in 1:
3: Many RVers drive with headlights on for safety,, Brake light and tail light lamps share same ground, if ground is loose a bump can spike the brake light line (Feeding back the tail light power) and killing CC
4: Short circuit on vehicle wiring harness (same as 3) Very rare
And the one other cause
Poor connection on the CC control or sense leads,, Or a bent pin, this actually happened to me, also rare but it actually happened to me, Took my dealer a week to find it, they charged me one hour labor (GOOD DEALER!!!!!!) The last day the technian and I were both working on it (Basically I was his remote control assistant). Found the bad connector, straightened pins and away we went.. Worked great.. Two day later Mr. Hit And Run IDIOT, played freeway billiards and put the red ball in the side pocket... Troopers are still trying to figure out how I kept it wheels down after he hit me,, but I did. And I still got to work on time (Body shop was across the road from the office).
Home is where I park it!