We need to know the chord/voicing sounding in m.8 - (1 measure after the Abmaj) to have a better idea of what the bassist is attempting to support with his bassline. His bassline there seems to imply a "Bb(major)...." chord of some kind. (Is the first note of m.8 a Bb??? or Bnatural?? Or, Is it impossible to tell, due to intonation issues?) Thanks.