I have my headlights set to Auto On and they work beautifully, coming on at dusk and in the early morning......even coming on if I enter a stretch of overhanging trees.
The wipers are set to Auto On and they work equally well.
I also have tthe headlights set to Auto Light Rain (I've checked 3 times to be sure) and they don't come on even in a moderate to heavy rain unless I manually turn them on. (Then I have to be sure to remember to turn them back to Auto On)
What step am I missing here? Can you not have them set to both Auto On and Auto Light Rain at the same time?