The IWSCHelper was being initialized in the SOAP activities init method.
Which meant if it was variant dependent on onStart() info. it would not have been reinitialized.
In 6.0 onStart() is called after the activities are initialized (after init() is called) make it more explicit.
This causes SOAP dataset/action calls that were dependent on onStart() to crash - whereas before they would have succeeded, but would potentially be wrong for all but the 1st execution if in a child query and dependent on onStart() context.