Excel spreadsheet applications and tips
How to solve if excel do not filter blank cells? (Filter checklist do not show blanks)
To avoid this issue, select the range before applying the filter function. Please refer to the following excel spreadsheet for example.
1. Before applying filter on column C, either select the entire column C or the data that needs to be filtered.
2. Select Filter option under Data tab. Now all items appear in the filtered list as well as filter checkbox list.
Search engine keywords for this question:
Filter blank cells in Excel 2007, 2010
How to include blanks in filter
Show blank rows in filter