Same problem here. 2x Windows 10 and 1x Android worked perfect on v5. Since the upgrade to v6 the first v6 install om Windows 10 + Google Drive sync worked fine. The android Google Drive Sync works too. But the second Windows 10 gives me the same error. The verification at Google is succesfully passed but still it gives the same error. Restart application shows no sync. Remove anr reinstall gives no solution.