HPCC-11900 Roxie graphs fail to display

Fixes HPCC-11900

Signed-off-by: Gordon Smith <gordon.smith@lexisnexis.com>
Merge pull request #6228 from GordonSmith/HPCC-11900

HPCC-11900 Roxie graphs fail to display

Reviewed-By: Miguel Vazquez <miguel.vazquez@lexisnexis.com>
Reviewed-By: Richard Chapman <rchapman@hpccsystems.com>