Use an Existing Custom List on the Matrix Item Assistant for an Inventory Item

Scenario:
To use the Use an Existing List option with a custom list on the Matrix Item Assistant for an Inventory Item, a new item field has to be created to associate the custom list to the item record.

Solution:

1. Navigate to Customization > Lists, Records, & Fields > Item Fields > New
2. Label: Enter Label
• Example: Custom List
3. ID: Enter _custom_list
4. Type: Select List/Record
5. List/Record: Select (The desired custom list)
6. Store Value: Enter Checkmark
7. Matrix Option: Enter Checkmark
8. Click Applies To 
9. Inventory Item: Enter Checkmark
10. Click Display 
11. Subtab: Select Matrix
12. Click Save

Note: Select the Type: List/Record first, then select the desired list for the Lists/Record field before entering a checkmark on the Matrix Option field.