On the "Citation" pane, for any given submission, if you set the publication type as "Book Section", click the "Update" button, and then set the publication type as "Book" and click the "Update" button, TreeBASE will give you a "Data Access Failure" error message with the description below.
Object with id: null was not of the specified subclass: org.cipres.treebase.domain.study.BookCitation (class of the given object did not match class of persistent copy); nested exception is org.hibernate.WrongClassException: Object with id: null was not of the specified subclass: org.cipres.treebase.domain.study.BookCitation (class of the given object did not match class of persistent copy)