We do not support historical syncing. Once this feature is enabled, you would need to edit an existing Opportunity record in order to sync it.
If you want to make an edit, it needs to be on one of the four fields that are syncing to ActiveCampaign. As a reminder these four fields are:
- Name
- Amount
- Stage
- Close Date
If updates are made to fields outside of this defined set, the Opportunity will not sync to ActiveCampaign.