I am merging several streams of data and I want to rename the value of the Status field when it is empty.  I have tried using Set Value with a condition Status is Missing and then changing the Status field to a Static Value.  However it does not replace the empty value.  I have also tried changing the condition to Status is present and rather bizarrely it still does not change it for these fields!?!

How can a field not be either there or not there?  Is anyone able to explain this weird logic which DPA appears to be operating under?