Assign to Project Role post function always assigns to a JIRA userID, if it matches the name of a project role, and no default users are defined in the project description.

When a JIRA userID matches the name of a project role, and no default users are defined in project description:

Assign to Project Role post function will always assign to this userID, regardless of who is defined in the role, (occurs even if the user is not present in any project role).