I know I will be corrected if I am wrong, but as I recall, the dome/map light is a 3 position switch. On to turn them on and stay on until the switch is turned off or to door positions. The door position allows the light to come on when the door is opened and stays on for a set period of time dims and turns off. The off position is so that you can open the door and not have the lights turn on.
It sounds to me that the light and switch is operating normally.
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BMW Z4
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