SP-1397 Backport of PRD-5176 - Blank values for the whole column when the first value in that column is NULL in the generated PRPT report - e.g. Excel (5.1)

NULL field fixed
Merge pull request #462 from AliaksandrDrebenchuk/SP-1397

SP-1397 Backport of PRD-5176 - Blank values for the whole column when the first value in that column is NULL in the generated PRPT report - e.g. Excel (5.1)