Even I have success with Walgreens too. You should have insisted them on choosing Canada from the list of countries when they get in to passport photo section. It should be really easy, and some lazy store associates just don't want to check this small thing. The only thing they cannot do is cutting because their cutters are meant got 2*2 photos.
They have for settings many countries, like UK, Germany etc. You could have insisted on asking a supervisor or could have visited different Walgreens. I have had to deal with two different Walgreens, both didn't knew about this, but were able to trace easily on my request.