The main sensor is in the middle of the dashboard, about 10cm back from the windscreen. (There's also another left of the steering wheel.)
I've noticed that if my stick-on window mount for my nav tablet shades the dash sensor, it messes with the auto settings because the car thinks it's in the shade. It can appear random, because the angle changes as you drive.
Perhaps you've got something similar going on?
If at first you don't succeed, that's one data point. - xkcd
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2011 Discovery 4 SDV6 HSE
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