Render MIDI file drums not rendered

  1. Launch Cubase
  2. Import Midi file.
    3 Render all
  3. All channels are rendered apart from Drum channel where I am given less than 1/16 of a bar , all the rest of the drums are not rendered.

Have replicated this with numerous midi files and cannot see whether I am missing something obvious. I pre-select all midi parts before rendering.