Cycling through prototypes with the arrow keys

Hey guys,
When you PREVIEW a screen, in the past (and randomly nowaday as well), it was possible to cycle through the pages with the arrow keys, without having to PREVIEW a screen each time. You would simply hit RIGHT or LEFT and you would preview the next and previous pages.
Why doesn’t it work anymore? I mean it works sometimes, but it’s very random. In the past it used to work all the time, now it works, but only sometimes. For example yesterday it was working, today it isn’t.