2.8: UV's not showing up in editor

I select some faces, hit U > Unwrap but the faces do not show up in the UV editor. Is there something I need to toggle?

is there a material for these faces ?

happy bl

It might be you are not in UV edit mode:

That should be selected on your left window.

Thanks for your replies RickyBlender and staughhost.
It seems I was not in UV edit mode, and putting in in that mode fixed things.