Remember the bug we helped uncover with Google Analytics that occurred on December 16, 2019? Well, it is still not fixed and probably won't be fixed for weeks. Google posted an update saying "We have revised our estimated reprocessing timelines for Dec 16-17 data to be ~2 weeks for 360 accounts and ~3 weeks for standard accounts."
In short, webmasters, SEOs and site owners were pretty concerned on December 16th and 17th when they looked at their analytics data from Google on the 16th. It was missing a chunk of data for many users. Google confirmed the issue the day later but now updated its estimate on when the lost data would be recovered to two to three weeks out.
The new message reads:
The problem with Google Analytics should be resolved for the vast majority of affected users. We will continue to work towards restoring service for the remaining affected users, but no further updates will be provided on the G Suite Status Dashboard. Please rest assured that system reliability is a top priority at Google, and we are making continuous improvements to make our systems better.We have revised our estimated reprocessing timelines for Dec 16-17 data to be ~2 weeks for 360 accounts and ~3 weeks for standard accounts. Please keep in mind we do strive to address this matter as soon as possible.
So be patient and hopefully after in January you will be able to backfill that data for your reporting purposes.
Forum discussion at WebmasterWorld, Google Analytics Help.