I might need more info but just off the top of my head

•  make sure that your watch list variable is part of the variable set in the catalog item (or case creation process) and is properly configured. Typically, this would be a type like "Watch List" or "List Collector" for users.

• After calling the createCaseFromProducer method, you will need to manually update the created case with the values from the watch list variable set.
  
  hope that makes some sense