F6.1 Footprint placement type must be set to surface mount
The Footprint placement type must be set to
Surface mount for SMD footprints. This is to ensure that these footprints are included in the Footprint position (.pos) file output.
To set the footprint placement type, open the Footprint properties window and select Surface Mount as indicated.
In KiCad 4.x, Placement type is called Attributes and Surface mount is called Normal+Insert.