Using 8.1.0 RC1, but had the same issues in 8.0.14, 15, 16
I have several users who are having issues using numeric inputs, text inputs, datetime, dropdown components. When clicking on the component, it gets focus and then immediately loses focus.
I think I have narrowed it down to devices that have a touchscreen, but still trying to confirm.
On my iPad, one of my popups works fine. But on another popup, clicking on the component does nothing. No popup keyboard opens up.
It looks like if any part of the popup is offscreen, then components stop working.