Andrea I have discovered that removing the curly brackets from the Native SQL query allows this test case to pass as expected.

The Hibernate Docs do show support for curly brackets in Native SQL, albeit only within examples for joining together separate entities - such as Example 566

https://docs.jboss.org/hibernate/stable/orm/userguide/html_single/Hibernate_User_Guide.html#sql-entity-associations-query

It seems unexpected that curly brackets would fail to work as expect with returning just a single entity