How to update issues after initial issue create

The update issue transition post function can also be used when issues are first created.

Edit your workflow - create a draft if necessary
Go to the Open step
Click on the Create Issue (1) incoming transition
Go to Post Functions
Add Update issues post function
Set other parameters as you need
Move the post function below the Creates the issue originally step and above the Fire an Issue Created event step - This is important!

Issue security - when updating the issue being created, add a post function for just setting issue security and position it above the Creates the issue originally step.