I can't reproduce this. The arrow works as I expect in my tests. There is a bug with how the auto scroll works in this scenario (regarding trying to make the selected element be displayed when the page loads).
This is now fixed. As it turns out, there are 3 different behaviors in browsers in RTL (they're consistent in LTR). Chrome was behaving as expected, but Safari and Firefox act a different way, while IE/Edge act a totally different way as well.
I've now implemented a system that normalizes the scroll positions (scrollLeft) and allows us to interact with them fairly consistently and that resolves this issue.