The following message is visible in the browser as well: “Message: Your workflow has encountered errors during deployment. Open the error console on the canvas to review the errors”.
With the introduction of the HTML mode of the mail configurations, the conversion of existing configurations missed an implementation of caching external reference configurations to allow for re-linking post conversion. This issue would only occur with SmartObject smartfields that does not relate to any item references in the same workflow.
External reference configurations are now cached prior to conversion to allow for re-linking.