Filter for blanks - nonblanks problem

[Paul]

I have columns in a worksheet, columns A thru J.
Columns F and J are date fields.
I need to filter both for non blanks.
When I apply the filter to one, I lose the ability to filter for
nonblanks from the other. The choice, Nonblanks, disappears.
Can anyone explain this behavior.

Thank you.

 

[mrice]

It might help if you select the entire area containing your data before
applying the autofilters. I've been able to select for non-blanks in
multiple columns when I've done this.