There are three values in the column: Yes, No and Blank. I was using the below formula to find a percent of customers who didn't have a mobile marked as 'No' over Total. Interestingly the denominator was incorrect, and when I tried to see what category is responsible, I found that the count of blank was incorrect. I changed it to COUNTBLANK but it still missed like 1,000 values. Do you have an idea why is happening here?