Hi @SNow Learner41,

There is a much easier and Out Of Box (OOB) field that is available and already handle this for you.

You don't need to write your own Client Script or Script Include.

Instead, follow the below steps. Essentially, any field from a related table can easily be pulled into the form. 

- Right-click on the form header and click on 'Configure > Form Layout'

- On the left-hand side of the 'Slush Bucket', navigate to the 'Assignment group field. You'll notice it's green and has a + symbol next to it. This tells us it's a related table where more fields are available.

- With the Assignment Group field highlighted, click on the top icon above the arrow icons in the center of the page between the 2 columns of data (See screenshot below)

- This allows us to now show the Assignment Group fields. 

- Either double-click on the manager of select the manager field and click on the right-hand point icon to move the field from the left side to the right side.

- You may now want to move the Assignment Group Manager field up to under where the current Assignment group field as shown below.

- Hit 'Save'

- Your form will now have the Assignment Group Manager field and it will display, update and change whenever the Assignment Group is populated or changed (Provided the Manager field is of course populated)

- Once tested, last but not least - delete/remove the Client Script you created, Script Include, and the u_manager field you created as they're not needed.

To help others (or for me to help you more directly), please mark this response correct by clicking on Accept as Solution and/or Kudos.

Thanks, Robbie

This last screenshot is just to show how you can use the OOB field called 'manager'. You'll notice it shows the who path to get to this value: incident.assignment_group.manager. You don't need to change or do anything more with it..