Post function Copy Value from other field not working

[Nannette Mori]

I added a post function to copy a value to another field within the same Issue.  I have a validator which requires the field at the transition "Prioritization" but I also added the Copy value from field to another field at the same transition.  Which means the field is requiring a value at Prioritization and also asking that value to be copied to another field at the same transition.  Do I need to add the post function to copy a value to another field at another transition then the transition I am requiring the field to be populated with a value?

Also I saw some documentation that there is a post function "Copy field value from Parent".  I do not have that post function in my post function list.  What version of JSU is that in - what is the Jira Misc workflow extensions?

[David Fischer]

JMWE (https://marketplace.atlassian.com/apps/292/jira-misc-workflow-extensions-jmwe?hosting=cloud&tab=overview) indeed offers the "Copy field value from parent issue" post function. 

As for your other question, I'm not sure I understand it. Post functions and Validators are independent, and Validators run before post functions.