We have had some crazy problems with the chrome extension where it has not been spying objects, We ran through the steps as outlined here but they didn't help. The solution was so bizarre that I thought it would be worth mentioning on here, so the problem it turned out was that we had not accepted googles privacy policy, once we had run through the T's & C's and accepted them spy worked without issue. Simply search for 'google privacy policy'
Hope this prevents anyone else getting as stressed as I did with this problem
I do hope I will never have to try it 
