After selecting the file, I click Import Users and am taken to a screen with two columns: Available Lists and Selected Lists. I move the list I want to Selected, but there is no action button and when I X out I got back to the prior screen for an endless loop.
Under Available Lists and Selected Lists there is an import button. You probably have to scroll down.
Thank you that was it. I have to enlarge the font and usually check, but the button was WAY off the screen.
It depends on you screen size/resolution if you have to scroll down or not. I have to admit that there is quite some space. At least when you only have few lists.
This is something @Alexandre could improve in a future release.