CF6 has no high stage bleed valve - it only has bypass valves at the booster (LPC) exit.
25+ years ago the CF6-50 could "hangup" out of ground idle - actually a low-speed compressor stall, no accel, slow EGT increase. It only occurred on "bleed off" takeoff - you could clear it by turning on A/C pack bleed. I doubt this is what happens on the CF6-80C2 though.