1. All layer types need to be defined before running "Netlist Extraction". Art001 --> Top Art002 thru Art011 --> Internal Art012 --> Bottom Note: The other layers need to be assigned also such as "Mask Top", "Silk Bottom", etc.
Note: If a file is non-essential choose layer type "Grahpic" or "Temporary".
2. The Drill file was not aligned to the gerbers (this is a common occurrence), so you will need to use "Align Layers" (a) Turn off all layers, except "Art001" (Top metal) and "Drl001" (Drill file) (b) Goto menu: Edit | Align Layers... (c) Select pad on layer "Art001" that requires drill hole (selection requires that you choose the edge of the pads). Note: I usually always choose the bottom leftmost hole that requires a drill. (d) Now select the corresponding drill hole on the drill layer "Drl001". Note: You will see the layer automatically align-up
Now your ready to run "Netlist Extraction" (menu: Tools | Nets | Netlist Extraction...).
Note: This was a 12 layer pcb using line fills (over 300k total objects) and the netlist extraction took me about 1 minute.
about 12 years ago
I had all the layers assigned and the drill layer aligned in the *.WRK file. It locks up when running in version 3.4.1 but runs fine in 3.4.6.Upgrading solved the problem.