The following describes HHH-13633.

A join fetched collection is not initialized, and Hibernate executes an extra query to initialize a to-one association when the following are true:

• enhancement as proxy is enabled (hibernate.bytecode.allow_enhancement_as_proxy=true)
• a stateless session is used
• results from a query involving an entity with a join fetched collection (that is normally lazy) is scrolled.
• join fetched collection has a to-one association with an entity that is an inheritance hierarchy.

HHH-13640 is related; it affects both Session and StatelessSession.