Roboto Thin for LayerSlider WP

Hi there,
amazing work you’ve done with enfold theme. Recently we stumbled over a little problem. We are trying to use Roboto Thin as font for the LayerSlider. It works on some machines, on others it does not (for example OS X + Chrome). We tried every tip we could find in this forum (like adding the font via functions.php, added the font via LayerSlider menu “Load Google Fonts” etc), we emptied every cache we could find, waited a couple of days … nothing. Perhaps somebody can help with this topic.
Best regards,
Team Clubmotion