When you add an activity during a modeling session, make sure you add all of the information to that activity in the workflow. You should not mark a different workflow active and then update that activity or relationship.
Workflow 1
Added activity 1.1.2.3
Added relationship
Workflow 2
Edit the added relationship from Workflow 1
If you complete or reload Workflow 2, PM Compass doesn't know about the "added" relationship; therefore, the system cannot find the relationship that was updated. You will need to omit that row in the Change log, complete the workflow, and then create a new change request to include the update. If you were to add the relationship in Workflow 2 and complete Workflow 2 first, PM Compass would know that the "Add" Change log entries need to be moved to the Workflow where the activity was added.