Auto-populating Field Isn't Mapping Properly Upon Submission

[jnchristie]

I have a variable on our Incident form for adding people to the Watch List of the Incident. I made a recent update to the form and was asked if we could auto populate the Watch list field from another variable on the form where the user selects another user at our institution. 

I was able to auto populate this field using the auto populate tab on the watch list variable and looks to be working. The problem I am now running into is that the value that is being auto populated isn't adding to the watch list on the record as expected when the form is submitted. It does work however if that field gets auto populated and the submitter then goes and manually adds an additional person to the watch list, it will add both the auto populated user and the new user to the watch list as expected. It seems to only not work when it's populated with ONLY the auto-populated value. 

The Watch List variable is field mapped, so it's not being populated by the script on the record producer.

Is there something I did wrong or should I just populate the watch list a different way?

[Zach Koch]

Here is a few alternative options

option 

Option 2