Why does the Project Name not appear as a selectable field/column in Sales Order Reports?

Why does the Project Name not appear as a selectable field/column in Sales Order Reports?

I just want to be able to add the Project Name as one of the columns in a Sales Order report. I'd expect to find it under Customise Report > Available Columns > Project Information? I've checked access permissions to the field and that all appears to be OK to.

Any suggestions as to where I should look?