matjashka,
A PDF is not a cad type of drawing, it is an image that has a drawing on it. Equally the PDF could be a photograph of a sunset or a poem.
To get around this, place the PDF on a worksheet first:
1 - start by creating a new worksheet.
2 - Set the scale of the worksheet to the scale you want the NCS12 marker to report.
3 - (Worksheets are located under the Navigator - View Map.)
4 - Save and place the worksheet view to the layout.
5 - Now the NCS-12 marker will report the scale of the worksheet, and incidentally the PDF's articifial scale.
Snap.
PS To double check the "effect": now place the exact same pdf directly onto the same layout sheet without passing through a "save and place view" operation, now look at the NCS-12 marker scale.