Problem:
You are trying to export a 3D STEP model of your PCB using a command such as
kicad-cli pcb export step MyPCB.kicad_pcb
but the resulting STEP file is missing all (or almost all) component models (i.e. only the PCB is exported).
Furthermore, in the output of the command, you can read
Cannot add a VRML model to a STEP file.
for every single component, for example
Add component R6. Cannot add a VRML model to a STEP file. Add component R21. Cannot add a VRML model to a STEP file. Add component C7. Cannot add a VRML model to a STEP file. Add component C16. Cannot add a VRML model to a STEP file.
Solution:
Add the --subst-models flag to kicad-cli in order to automatically substitute VRML models with STEP models:
kicad-cli pcb export step MyPCB.kicad_pcb --subst-models
After that, all available component models will be exported just like in the viewer.