When I double click on the "Filename" field to export (regardless of the format of export) nothing happens.  So, of course, when I click on "Export" it says "You have to enter a filename (Close)".
 

Inkscape 1.3.1 (9b9bdc1480, 2023-11-25, custom)

    GLib version:     2.72.4
    GTK version:      3.24.33
    glibmm version:   2.66.2
    gtkmm version:    3.24.5
    libxml2 version:  2.9.13
    libxslt version:  1.1.34
    Cairo version:    1.16.0
    Pango version:    1.50.6
    HarfBuzz version: 2.7.4

    OS version:       Ubuntu Core 22

How to export PDF with Layers?

James Bowery: The filename field is for text entry. Single click then type your filename. Or try single click on the adjacent folder icon.

miquel: All visible Inkscape layers are exported to a flat pdf with no layers.

PS. You're more likely to get a reply if you create a new topic rather than asking unrelated questions in an existing topic.

I need two separate layers in one PDF file, for example, one layer is the design and the other is the lines for cutting.

Single click and type was the FIRST thing I tried before I searched the web and found a video that said to double click.  

Neither works.  There is no way to enter a file name.