Currently, if you use the post-function that allows you to copy a parent's value from any field you specify, it will cause an error when testing in workflow.

This happens for copying the Fix Version value from a parent to subtask. When transitioning an issue, the following error appears "Error creating issue: Unable to copy value from field 'Labels' to 'Labels'"

In order to fix this, you must move the post-function to the end of the other post-functions.