PDF Inclusion Query

I just copied a PDF document to a box set

There is a master folder, and 8 subfolders for each CD. I put the PDF into the master folder along with a JPEG “folder”.

The PDF didn’t show up the JPEG did , I rescanned still nothing . I finally moved it to CD1 folder and it showed

Isn’t this rather illogical as the PDF refers to the Whole box not just CD1 ?