Possible Bug With Taxonomy Advanced Field

When using the Taxonomy Advanced Field in the "Select Tree" configuration with terms arranged in a parent/child relationship and it being a required field, I can successfully save the post. However, if I update another field and need to save the post again, I get a warning saying the field is required. This is in spite of both the parent select and child select fields being filled in. In order to get the post to save, I am forced to select a different parent and child.