You must add a preview picklist value to the Async Action Info object manually.

To add preview picklist value

  1. Go to Setup, in the Quick Find box, search and select Objects.
  2. From the list of objects, select Async Action Info.
  3. From the Custom Fields and Relationship related list, click Async Action.
  4. Scroll down to the Values section and click New.
  5. Add a new picklist value Preview. Make sure the list of restricted values looks like the following:
    • Preview
    • Submit
    • Cancel
    • Approve
    • Reject
  6. Click Save.