I am currently working on developing a full screen slider with a unique feature on the last slide: a horizontal scrolling area. To achieve a smooth animation, I am using CSS translations to bring the div within the viewport.
Oddly enough, the scrollbar does not function correctly unless the window is resized.
My theory is that when the scrollable div is initially positioned outside of the viewport, Chrome does not render it (potentially for performance optimization).
It seems that upon resizing the window, the entire layout is recalculated and redrawn, allowing the scrollbar to work as expected.
If you would like to see the issue in action, you can view this JSFiddle that I have created: http://fiddle.jshell.net/f3thbjqc/6/show/
Additionally, I have created a video showcasing the problem. You can watch it here: https://i.sstatic.net/QZUTA.gif
My current setup includes a Mac OS High Sierra operating system. Both Chrome 69.0.3497.100 and Safari 11.0.1 (13604.3.5) exhibit the same behavior, whereas Firefox does not show the same issue.