Consider class B deriving from class A. There is an entity C referencing class B as a component. Envers includes the properties of class B, but ignores the properties of class A. In normal queries, NHibernate does not ignore the properties of class A. I attached a unit test for demonstration (using an SQLite database).
However, there is a workaround for this: Make class A's properties virtual and override them in class B. But it would be nice, if Envers includes them without this ugly workaround.