message: Handle special case in BeginStep properly. First BeginStep when there is one step in file already loaded during Open.
diff: @@ -59,6 +59,7 @@ StepStatus BP4Reader::BeginStep(StepMode mode, const float timeoutSeconds)
  // used to inquire for variables in streaming mode
  m_IO.m_ReadStreaming = true;
  StepStatus status = StepStatus::OK;
  +
  if (m_FirstStep)
  {
  if (m_BP4Deserializer.m_MetadataSet.StepsCount == 0)
  