In January of 2018, our company changed from an instance of Adobe Analytics that was run by our third party website provider to an instance of our own. The code stayed the same but now Adobe Analytics is reporting higher revenue than our order management system. Prior to January 2018, revenue was ALWAYS lower. This is causing problems within our organization regarding reporting...especially on the digital marketing side as they can only report from Adobe Analytics. What could have caused this shift and how do we fix it so our numbers aren't dramatically different going forward?
You need to verify what pages were involved at time of revenue attribution pre and post Account move. When you say "code is the same" do you mean DTM analytics code? Are you using DTM?
The actual purchase event could now be fired at a different time of order process. Another variable I find critical that is often overlooked and not captured at time of data collection is transaction ID. The Trans ID can then be correlated to any back end to ensure values match as expected.
Since Marketing is involved I also would look at integration with (digital campaigns) so SEM and Digital banner spends can properly be correlated. Are you using AMO or Google Adwords? Both?