Since I can't seem to properly get Google working, I set up Twitter.
On first site entry, a user sees the number of login options which is currently Facebook and Twitter.
I've set up both.
Testing Twitter seems to authenticate correctly. Problem is, that's all that happens. No user is created and the authentication screen just disappears.
Facebook now: Click FB icon, authentication popup appears and then disappears. No user created.
BUT when I then click the LogIn button on the Login Widget, the FB user is created and logged in.
The same behaviour happens with Twitter too - need to click the Login button to complete the action.
That's just plain weird and a poor user experience since no potential user is ever going to try that.