On the 2018s, the interior light only turns on the center lamp, not the 4 surrounding it. The 4 seem to be computer controlled, not a switched, because if you turn one on, then after the interior lights turn off, it remains off the next time the interiror light turns on.
Is it possible to program all 4 lgihts to turn on when the center light turns on? It would be easier than swapping out the light fixture for a 2019.