I haven't tried wiring two CC switches together but the chattering behavior matches K-Line switches. The switch controllers use DC polarity to light the correct LED and drive the switch motor. RH and LH K-Line switches must use a matched controller. You might have a similar situation where diodes provide a feedback loop causing the chatter on one switch and blocking the signal to the non-responding switch.
Your crossover uses two RH switches so you don't get the mismatch chatter.
Try using a SPDT momentary contact switch (without the lights) wired between the track ground and the insulated rails.