ERROR [TransformSDB] OpTable : Not join identity

[Rachel Han]

Hi list,

I am quite new to jena/sparql. Recently I have spotted an error while
running any sparql query with "values" keyword.
It gave me this line in the log : ERROR [TransformSDB] OpTable : Not join
identity

e.g.
PREFIX dm: <http://learningsparql.com/ns/demo#>

SELECT * WHERE { }
   VALUES (?color ?direction) {
   ( dm:red  "north" )
   ( dm:blue  "west" )
}

We are using
jena 2.10.1,
jena-arq 2.10.1,
jena-sdb 1.3.6,
jena-tdb 0.10.0,
jena-iri 0.9.6

mysql database version 5.7
sparql version 1.1

Would anyone have the same issue like this? Please help :)

Thanks in advance.

Cheers,
Rachel