Mobile Version Of My Site Has Disappeared

Hi guys!
Loving all that you do, really cool to see the changes and optimisations being made to my site.
I've run in to a bit of a problem though. Since installing Hummingbird, the mobile version of my site has just disappeared - all mobile users are being shown the desktop site; not a good experience at all.
I've granted support access and am very much looking forward to your response :slight_smile:
Thanks,
James