Only contacts who have been sent an email (not including internal emails) in your workflow and later go on to meet the goal criteria will be counted toward the conversion rate on the Performance tab.
The goal conversion rate and number includes contacts who complete the workflow after having been sent an email in the workflow and later meet the goal criteria, even though they are no longer in the workflow.
If a contact meets the goal criteria while still active in the workflow, but they haven't been sent an email from the workflow, they will still be unenrolled from the workflow, but they won't count toward this number. An email must be sent to the contact; this does not include internal emails sent via internal email actions in the workflow.
Contacts who meet the goal criteria while active in the workflow will still be counted towards the "met goal" number even if they later no longer meet the criteria.
If a contact is suppressed from the workflow as a result of joining a suppression list or if a contact is unenrolled from the workflow after being enrolled in another workflow, and they later meet the goal criteria, they will not be counted towards the goal criteria number.