scrollToExact("text") function usually works well inside a dropdown list. Try that.
For Date Picker, in my project I am relying on sendKeys for each individual edit box with index [ex: 0 index for Date, 1 index for month and 2 index for Year ...].. this is not reliable, but works for now
I will explore more and let you know, if I get any better solution.
Note : Answered the same in Github portal as well