Post function "copy value from other field" does not work on create transition for Assignee field and Reporter field

Issue Summary

Post function "copy value from other field" does not work on the create transition for Assignee field (Inheriting the value from the parent issue to a sub-task)

Steps to Reproduce

1. Navigate to your project settings > Workflows > Find the workflow related to sub-task issue type >Edit > Click on the create transition > Post functions
2. Configure the Post function "copy value from other field", copying the assignee field from parent to the sub-task:                       
3. Save the workflow draft
4. Create a sub-task in an assigned issue

Expected Results

when creating a sub-task, the Assignee of the parent is copied to the sub-task.

Actual Results

The assignee is not set.

Workaround

Use a Jira automation rule as described in the following community thread:

• https://community.atlassian.com/t5/Jira-questions/Copy-Assignee-and-Reporter-display-name-into-a-custom-text-field/qaq-p/1160433