Flux cannot display ISO values - gives error

I have a 3D AC Flux model. Solving does not produce any errors. But trying to display iso values fails with below error. What are possible things I have done wrong?

OCRI04 => Number RB.F3D.REG_VOL(0) out of bounds
OCRI04 => Retrieval of INTEGER attribute aborted
RVRTY3_1 => Failed
RGR2SU => Retrieval aborted
RGR1SU => Retrieval aborted
FARLVF => failed
EQCFFB => Definition of isovalues aborted
PISO_ENUM => failed..
executeAlgo_c => failed
stdcom.error.SoftwareFortranException: executeAlgo_c : Execution failed.
Failed execution
at cad.core.common.error.ErrorManager.createFortranException(ErrorManager.java:174)
at cad.flux.kernel.dbmanager.FGCProjectDbWrapper.executeAlgo(Native Method)
at cad.flux.kernel.dbmanager.FGCProjectDbAdapter.executeAlgo(FGCProjectDbAdapter.java:936)
at cad.flux.kernel.dbmanager.FGCDbManager.executeAlgo(FGCDbManager.java:151)
at cad.flux.kernel.FGSupervisor.executeNativeCommand(FGSupervisor.java:2249)
at cad.core.kernel.Supervisor.executeCommand(Supervisor.java:2117)
at cad.core.kernel.Supervisor.executeMethod(Supervisor.java:2230)
at jdk.internal.reflect.GeneratedMethodAccessor368.invoke(Unknown Source)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.python.core.PyReflectedFunction.call(PyReflectedFunction.java:190)
at org.python.core.PyReflectedFunction.call(PyReflectedFunction.java:208)
at org.python.core.PyObject.call(PyObject.java:521)
at org.python.core.PyObject.call(PyObject.java:526)
at org.python.core.PyMethod.call(PyMethod.java:171)
at pydb$py.executeMethod$212(pydb.py:1733)
at pydb$py.call_function(pydb.py)
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:168)
at org.python.core.PyFunction.call(PyFunction.java:437)
at org.python.core.PyMethod.call(PyMethod.java:156)
at pydb$py.call$179(pydb.py:1504)
at pydb$py.call_function(pydb.py)
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyBaseCode.call(PyBaseCode.java:306)
at org.python.core.PyBaseCode.call(PyBaseCode.java:197)
at org.python.core.PyFunction.call(PyFunction.java:485)
at org.python.core.PyMethod.instancemethod___call__(PyMethod.java:237)
at org.python.core.PyMethod.call(PyMethod.java:228)
at org.python.core.PyMethod.call(PyMethod.java:223)
at org.python.core.PyObject.invoke(PyObject.java:3634)
at org.python.core.PyInstance.instance___call__(PyInstance.java:377)
at org.python.core.PyInstance.call(PyInstance.java:372)
at org.python.core.PyObject.call(PyObject.java:455)
at org.python.core.PyObject.call(PyObject.java:459)
at org.python.pycode._pyx234.f$0(<input>:1)
at org.python.pycode._pyx234.call_function(<input>)
at org.python.core.PyTableCode.call(PyTableCode.java:173)
at org.python.core.PyCode.call(PyCode.java:18)
at org.python.core.Py.runCode(Py.java:1713)
at org.python.core.Py.exec(Py.java:1757)
at org.python.util.PythonInterpreter.exec(PythonInterpreter.java:277)
at cad.core.kernel.components.PythonWrapper.runCode(PythonWrapper.java:655)
at cad.core.kernel.components.PythonWrapper.runsource(PythonWrapper.java:650)
at cad.core.kernel.components.PythonWrapper.runsource(PythonWrapper.java:625)
at cad.core.kernel.components.PythonWrapper.runsource(PythonWrapper.java:620)
at cad.core.kernel.components.PythonWrapper.execute(PythonWrapper.java:665)
at cad.core.kernel.components.PythonWrapper.executeFunction(PythonWrapper.java:733)
at cad.core.kernel.encoder.CommandServerRequestsInputPlug.executeCommand(CommandServerRequestsInputPlug.java:79)
at stdcom.protocole.commandserverrequests.CommandServerRequestsRouter.executeCommand(CommandServerRequestsRouter.java:70)
at stdcom.protocole.commandserverrequests.CommandServerRequestsOutputPlug.executeCommand(CommandServerRequestsOutputPlug.java:111)
at cad.core.frontal.decoder.FrontalDecoder.executeCommand(FrontalDecoder.java:694)
at cad.core.frontal.actions.implementation.GeneralAction.executeBox(GeneralAction.java:286)
at cad.core.frontal.actions.implementation.GeneralAction.postAct(GeneralAction.java:254)
at cad.core.frontal.actions.implementation.GeneralAction.interpret(GeneralAction.java:315)
at cad.core.frontal.components.box.frontaldialog.FrontalDescriptorDialogBox.internalRun(FrontalDescriptorDialogBox.java:296)
at cad.core.frontal.frontalthread.WorkerThread.executeImplementer(WorkerThread.java:226)
at cad.core.frontal.frontalthread.WorkerThread.run(WorkerThread.java:274)