last opened is blank problem

I wanted new files that have never been opened to be labeled orange. I tried using "last opened is blank"

this apparently doesnt work. instead I had to use "date last opened is before date added" which is a bit different.

Why wont is blank work?
has the file been opened somehow?

Doing a quick test of creating a file, it seems to get a last opened date that is the same as the creation date. So, it seems that files always have a last opened date.