Reference not found error when deploying workflow

Issue

A Missing Reference error occurs when deploying a workflow:

Error Code

Missing reference at ItemReferenceField ‘AA’ in InlineFunction ‘Split’ in Event ‘Sent Email’ in Activity ‘Send Email’. Error: While trying to resolve the following reference root.configuration.itemReferences[{“internalId”:33}], an error occurred: reference not found.

Resolution

There is a reference called 'AA' that is used in a Split function on the CC field of a particular Send Email step. This was resolved by removing the Split function and then adding it back with the same AA reference on the Send Email step.