A Google AdSense Help thread has confirmed reports of Google AdSense reports not showing earning values.
It was reported several times in the forum, but a top contributor confirmed the issue on January 26th.
Many publishers using Blogger have been reporting that their earnings are not displayed under the Monetise tab. If you have this problem, please post here, so that the scale of the problem can be gauged, and avoid duplicate questions and answers.
Yesterday, a Googler said they are aware of the issue:
Our engineers are aware of this issue and are working on a solution. In the meantime, you can access your earnings data by logging into AdSense directly.
I apologize for the inconvenience.
There is not estimated time as to when Google will fix the issue, but they are aware.
Forum discussion at Google AdSense Help.