Try to book lax-can-syx in September in business.
searched using CZ sky pearl program, wide open availability every day.
searched using delta, wide open pretty much everyday with multiple flights available each day
called AA, talked with a few agents, no seats available at all each day in September even for the lax-can segment. The agent did find one coach seat available on one day though, and she seems need to request CZ to release that seat to her, which takes only a few minutes.