I was driving my XJL once on a kind of twisty two lane road that had fences, then hills, then open area, and kept transitioning on the passenger side. Eventually a notification came up and said blind spot not available, the terrain and transitions confused it. After I stopped/started the car, it went back to normal, fault cleared. I suspect the same could be the case where it is environmental based and the confusion is the resulting unavailable notification you get for lane keep assist. I checked with my OBD II reader later and didn't find any residual faults present.