When sorting files with multiple heading lines (attached fille 1), the first output row is incorrectly SUPPRESSED from the output sorted file if the sort is done on a column with concatenated heading lines (column W in the attached file 1) - see attached output file 2 where line 5 in the input file has been suppressed. 

The sort works correctly if the sort is done on a column with the full number of heading lines (column Y in the attached file 1) - see attached output file 3.

In this case there were 3 input heading lines, but the problem is the same with files with 2 heading lines when sorting on columns with concatenated headings.