An Automation Process is showing in Process History as not complete, or it does not create the email or document until you complete a Task created in the process.
The reason for this could be that a step in the automation has the task set as a "blocking" task and has Blocking set to "On". These tasks are displayed with an icon of a tram with an alert symbol.
Until the status of the Task is set to "Complete", the next step in the process or the overall completion of the automation, will not happen. This could also be the case if the Process only holds one step.