Symptoms

Accessing a workflow task by double-clicking or right-clicking show an additional outcome step that does not exist.
Hovering over the same workflow task and clicking the side outcomes icon shows the correct outcomes.

The form has been behaving weird at that step - i.e. it does not show the customized message set in the Actions at that step.

Also, the steps show in reverse order on the actions form, which is strange for users. I have rebuild all the workflow steps several times, which has worked before, but this error did not go away.
 

Diagnoses

The workflow somehow disassociates the path from the action.
 

Resolution

Select 'generate outcomes' for the affected actions, connect the generated paths to the rest of the workflow path, and remove the original outcomes.