by Doug Stevens.
Solved, and the solution was related to soapClient class headers. It wasn't waiting for a response from the server before moving on as it processed the enrol_manual_enrol_users asynchronously. I added 'features'=>SOAP_WAIT_ONE_WAY_CALLS, to the options and presto, everything worked!
$clientm = new SoapClient ($wsdlm, array (
'encoding' => 'UTF-8' ,
'cache_wsdl' => WSDL_CACHE_MEMORY,
'compression'=> SOAP_COMPRESSION_ACCEPT|SOAP_COMPRESSION_GZIP,
'soap_version'=>SOAP_1_2,
'keep_alive'=>true,
'exceptions'=>true,
'features'=>SOAP_WAIT_ONE_WAY_CALLS,
'trace'=>true
) );