We’ve noticed when you click the Date Picker control and the Calendar selection section pops open, if you then scroll the page, the calendar section stays stationary on the page instead of either moving with the Date Picker control or disappearing from the screen.
Thanks for your question. After replicating the issue, I experienced the same behavior when I scrolled the page. This is a bug with the control and we thank you for alerting us of it. We will have our development resolve it.