When I tried to pull March data from Tableau, I found the visits, pageviews etc. metrics showed in tableau did not match with GA. And I looked data by days and found the mismatch only happened for Mar 2nd, 3rd and 4th. Anyone had similar problem before?
I'm not a GA expert, but I have found that if I add too many dimensions the data won't match what GA displays. I don't understand the GA connection enough to explain why this happens, but maybe it will help you pinpoint the issues.
This is what I use for Session and Pageview counts.