Unexpected SQLException [ java.sql.SQLSyntaxErrorException: ORA-00903

We're using Fuseki 2.4.0 (Oracle supported one) to expose a Graph created with a set of views.

These views are extracting information from external Oracle databases using a external link (Public link) accessing to another Oracle database.

When we want to extract all predicated (
SELECT distinct ?predicate
WHERE {
?subject ?predicate ?object
}

An error ORA-00903 is trigger with a large stack.

Some potentially important notes:
1) views are extracting a subset of fields from external databases
2) the ORA-00903 issue is appearing also when views are created with an InnerJoin.
3) Same SPARQL query works fine from Oracle SQL Development, which drives me to think it's an issue on Jena or Fuseki

I'll post java exception stack in a comment