[Resolved] Manual test execution works, automation does not.

I have tried a very small Groovy script incorporating the suggested workaround. Here is the code:

 def vntProject = testRunner.testCase.testSuite.project;

 // for loop for controlling test suite in use
 for( vntTestSuite in vntProject.testSuites )
 {
  //assign the test suite to a variable
  vntTestSuite = vntProject.getTestSuiteByName( vntTestSuite.key );

  // assign test suite name to a variable
  strTestSuiteName = vntTestSuite.name.toString();

  // ignore the Groovy test suite as we don't want to run this as this is the driver script - without this execution would get into an infinite loop
  if( strTestSuiteName.indexOf( "Groovy" ) == -1 )
  {
   // log the name of the test suite in use
   log.info( " > TEST SUITE NAME IS: " +  strTestSuiteName );
   log.info( "hello" );
   testRunner.testCase.testSuite.run( null, false );
   log.info( "world!" );
  }
 }

However the code executes to the point of writing "hello" into the Log Output pane but then hangs at:

testRunner.testCase.testSuite.run( null, false );

It never gets beyond this so never writes "world!" to the Log Output. No other log tabs contain any further information that helps me track the nature of the problem down.