Hibernate + Spring + JTA + Oracle 11g not working with Fuse

Issue

We're seeing a problem with the transaction commits here. Hibernate fails to flush before the commit. If we manually flush, then everything works:

        public void add(DataPoint dp) {
                entityManager.persist( dp );
                entityManager.flush();   <=== add
        }

I tried playing with the auto-commits but this didn't help:

<property name="hibernate.connection.autocommit" value="true" />
<properties>
            <!--property name="hibernate.connection.driver_class" value="org.h2.Driver"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/-->

            <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/>

            <property name="hibernate.show_sql" value="false" />
            <!--property name="hibernate.hbm2ddl.auto" value="create-drop"/-->
            <property name="hibernate.hbm2ddl.auto" value="update" />
            <property name="hibernate.archive.autodetection" value="class"/>
            <property name="hibernate.connection.autocommit" value="true" />
        </properties>

Note, that using the H2 database everything works as expected.