Possible bug in atmega2560 board lib, or errata for specific manufacturing run?

Hello All,

I started over here: Interrupts not working when in sleep mode · Issue #84 · MCUdude/MegaCore · GitHub but it seems to either be a manufacturing problem or a board lib problem.

Essentially on the atmega2560, using the sample wake from sleep code here: Arduino Playground - ArduinoSleepCode

If you enable the internal pull-up resistor on whatever pin you're dealing with and try to use the FALLING edge to wake the micro, it will not wake, but if you use LOW it will.

Edit: I tested on two different chips with date codes:
16AU 1616
16AU 1726

Thanks,