We will update this post as we work to resolve this issue. As always, you can visit the Google Analytics Status Dashboard to see the current status of Google Analytics.
Update 5/13/11 3:45 PM PST
April data affected by this issue has been restored for all days after and including April 20th.
Update 5/11/11 10:30 AM PST
We want to reiterate that no data was lost due to this issue, and we’re working hard to make the April data fully available in your Analytics reports. Our current timeline for restoring full functionality for April data is approximately 12 days, by May 23rd. We’re doing what we can to shorten this period. We’re restoring the data day by day so you will see it come in to your account over time and not all at once. Keep in mind, that you can view the affected April data through the standard reports.
Secondly, we’ve seen some comments about Fast Access mode and its relation to the issue. Fast Access mode is a change, in name only, to how we label a sampled report to help better explain why sampling happens in Google Analytics. This change was not responsible for the issue with April’s data.
We’ll continue to update this post with developments we work to completely resolve this issue.
Posted by Trevor Claiborne, Google Analytics Team