When you have multiple actions that you want to run in a parallel way you can link them and use the junction in order to wait for all actions to be finished before continuing.
Here’s the Technet explanation : https://technet.microsoft.com/en-us/library/hh206089.aspx
Now consider the following example :
We use the logging IP in order to grab some information in service manager and save it in a custom field. This is accomplished by calling several sub runbooks.
It looks like this :
Now if we return no data from the junction then our get log data is not succesful as the logging ID is empty.
If you run the tester you recieve no error but the logging id is empty.
While the action clearly stated to use the logging_id from the start activity.
Now if we add the return activity from our previous branch we recieve exactly the same issue.
I had to add a link to our first subrunbook in order to be able to retrieve the Logging_id from our first start action. Then it works.
And set the returned data from the junction to this activity.
At last success.