If you are a US publisher, you may have been using the Google Pack referrals. Unfortunately for those publishers, Google also failed to track those conversions for 24 hours.
We wanted to let you know that Google Pack Referral conversions were not recorded for a 24 hour window beginning early July 5th and ending mid-day July 6, Pacific Time. Conversions from this period won’t appear correctly in your reports and you won’t have received the related earnings.
Please know we’re working hard to reimburse you for the lost revenue in the coming weeks. We sincerely apologize for any inconvenience this might have caused.
The Google AdSense Team
This is quite a tremendous error that Google made, and could lower the trust that some publisher’s have on the entire program. It will be interesting to watch and see how they rectify this. They could track down some of the data (do they really not have backups and backups of those backups of these stats?) or maybe give publishers money based on the average conversions they might have had on a given day for Google Pack. Fortunately for publishers, it did come on a day that many saw lower traffic due to it being the day after the Fourth of July in the US.
Forum discussion at DigitalPoint