Copy previous results to parameters? with Execute for every input row? unchecked

I have a job with two transformations. The first one has a "Copy rows to result" step. In the second one, I am trying to use "Copy previous results to parameters?" I have set up the Parameters tab to pass one of the stream columns to a parameter.

If I check "Execute for every input row?" then everything works. However, if I uncheck that box, the value from the stream column is not passed to the transformation as a parameter.

I thought that if "Execute for every input row?" was not checked, the transformation should execute once and use the stream column value from the first row of the results. Is that wrong?

Thank you.