UPDATE: As of January 23, Google said it has fixed the problem and past data should be restored “in the coming days.”
Google has confirmed a bug that causes conversions from Google Analytics to not be imported into AdWords properly, which can cause issues with any campaigns using this data for optimization. The bug has been reported by posters at WebmasterWorld and discussed at Search Engine Roundtable, with some posters saying they noticed the problem begin as early as January 6.
Says a Google spokesperson:
We’ve recently been experiencing a technical issue affecting a small number of advertisers who are importing engagement-based Google Analytics goals into AdWords, such as page depth and time on site. Advertisers who are importing URL-based goals into AdWords, like a visit to an order confirmation page, have not been affected. Our engineering teams are working on a fix and we’ll provide an update when it’s available.
The spokesperson confirmed that advertisers using Google’s automated bid optimization tools based on these engagement goals could be affected. The effect would be lowered bids and reduced traffic, because AdWords isn’t aware that conversions are actually taking place.
For the time being, some marketers suggest affected advertisers switch their CPA campaigns to CPC until Google resolves the issue, and the tools have the correct data to make optimization decisions. The company hasn’t given an estimated time for the fix to be complete.