This is affecting the Hibernate second-level cache simple tutorials where queries are executed outside transactions.

The problem is that the new integration for the query results (result of ISPN-9075) does not verify if there's an on-going transaction before registering a transaction completed synchronization where the query cache is updated.

As a result, when a non-transactional query happens, the transaction synchronization callback does not happen and the query cache is not updated.

Fix exists in 9.4.x/master and just needs backporting to 9.3.x.