The "Copy Value From Other Field" post function doesn't work on "Create" transition for "Priority" field

Issue Summary

Using the "Copy Value From Other Field" post function to copy the "Priority" value from parent issue to sub-task it doesn't work.

Steps to Reproduce

1. Add a post-function "Copy Value From Other Field" at "Create" transition
2. Then, set up as per screenshot below :-
   
3. Publish the workflow
4. Then, create a sub task issue.

Expected Results

The subtask priority updated with the same priority value from the parent issue.

Actual Results

The priority field at subtask issue doesn't updated.

Workaround

Use the "project automation" feature to update the value.