It isn't related to ambient light, but it could have been a bad contact on either the microswitch (sliding cover) or visor mount (when it rotates down), likely from not having been used for some time. My money would be on the swing-down visor swivel, is it is a sliding contact instead of a microswitch.

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2007 X3 3.0si, 6 MT, Premium, White

Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue