Attributing sessions and ecommerce data incorrectly
like any publisher we tag landing pages with UTM parameters then use then in social media posts, email campaigns...
Google analytics is attributing sessions and conversions to campaign parameters that we stopped using in our campaigns long time ago. For example, we are seeing recent sessions and transactions in March and April 2017 on landing pages that we stopped using in July June and 2016. We have similar cases all over GA property.
We don’t know whether Google Analytics is simply attributing conversions to wrong campaign parameters, or we actually have sessions coming from these URLs somewhere.