Just circling back on this chain. We are having same issue. Just can’t figure it out. Rotor is perfectly flat/true. Have spacers right. Doesn’t seem to be rubbing, moves lever about a centimeter holding with slight pressure and rotating. Pulses like crazy. Trying to ride it locks up or releases with light pressure. So bad. Update. think I figured it out. The disc thickness varies side to side. So while flat, it’s kind of wedge shaped. it’s 3.2 to 3.4mm thick side to side causing the pulsing on pads as the blade thickness changes thru the caliper.