Hello again.
Authentications to Google Analytics and Google+ should be working fine now.
After troubleshooting this issue earlier today, we found that the authentication failures for GA and G+ were apparently due to erroneous responses coming back from Google. It appears we weren't the only ones experiencing this issue.
At any rate, things began to clear up around noon (US Pacific time), and periodic tests since then have all indicated that GA / G+ connections to Moz Analytics are working normally. Thanks for hanging in there, and please don't hesitate to contact our friendly Help team if you experience any further issues.