I have the same issue and bothers me a lot.
I write in for example "nrk.no", then I click enter. The address bar is then deselected but nothing more happens. I then have to click in the address bar and click enter, then it works.
It seems that after it've happened, the address bar works fine for a while, until at some point it fails again for no appearant reason. I believe it have mostly happened when I've started a new tab, although I think it's also happened for an existing tab. I'm on version OS X 10.9 (13A3017).