When Creating an Issue using the REST API endpoint “rest/api/3/issue”, Post function to Copy field data is ignored

Issue Summary

When Creating an Issue in JIRA using REST API endpoint “rest/api/3/issue” and if the user has a post function in the Create Issue Workflow to Copy the Text/data from Multine-Line CustomField to the Default Description Field, the post function doesn’t work/execute.

Steps to Reproduce

1. Create a Multiline CustomField.
2. Update the Project workflow such that the “Create Issue” Transition has a Post-Function which copies data from one field to another. In this example from the MultiLine CustomField to Description Field.
   
3. Using the REST API endpoint “rest/api/3/issue” create a JIRA issue.
4. Pass the Value/Text content in the MultiLine CustomField in the payload. This content is expected to be copied over to the Description Field.

Expected Results

• The Issue gets Created and the Post-Function is triggered with the data in the MultiLine CustomField copied to Description Field.

Actual Results

• The Issue is Created, but the Post-Function doesn’t execute.

Workaround

The Post-Function works as expected when the REST API endpoint is “rest/api/2/issue”