When reassigning transaction it does not search by last name or preferred name

Summary:

When reassigning transaction it does not search by last name or preferred name

Content (please ensure you mask any confidential information):

We noticed that when we reassign a transaction to a user, it does not search for that user by last name or preferred name, just first name. When you go into advanced search, you can search by last name but not preferred name. It looks like the standard search uses Display name but just the first name. Did you experience this as well? Is there any way to change it?

Version (include the version you are using, if applicable):