Maybe someone else has ideas, but I would need a sample workbook to see what's behind that data.
If you are concerned about proprietary data, you can anonymize using the steps shown in the video linked here:
I wouldn't need all your data. Just enough Child Plus IDs to see a few of those null rows. (And a few that aren't null, of course.)
There is difference between blank and Null, since it appears Blank so First You need to Put Something there for Blanks and then Count
Once you get N/A in your Data Count them but as Joe Said, It is a Guess work from Me. We Need workbook to help you.
Thank you so much both Joe and Deepak for speedy reply and resolution.
IFNULL(Lookup(ATTR(status Description),0),"N/A") works perfectly.