When running in an App Server that is not JBoss we need to configure the "hibernate.transaction.jta.platform" to bind the JTA resource to the current EntityManager. For instance, using WebLogic 12c:

<property name="hibernate.transaction.jta.platform" value="org.hibernate.service.jta.platform.internal.WeblogicJtaPlatform" />

I think that a new parameter is needed on the persistence setup command.