Chris,
We have had multiple failures of a CD54HC123 but all pieces were destroyed before failure analysis could be performed. One unit finally went to analysis and found "fused open" Vcc wire bond lead and evidence of damage on GND lead. No obvious physical damage on the die. I suspect 1A and 1B inputs are very slow transitions (monitoring power supply voltages) and far exceed the specified transition times. Is this type of damage consistent with the transition issue.
