How to count x's in column but not blanks

Thanks SHG

Question . . . in the upper left corner of the results field, cells with a zero or rather blank value has a the corner shaded black. I've seen this before, but don't know why it happens.

Your formatting suggestion works fine. Thanks

What do you see when you hover over it?

Nothing hovering over it.
When I click on the cell, a box pops up about 1/4" square with a diamond shape inside and an ! inside the diamond.