I wonder if there’s some 64 line I/O somewhere with a couple traces bridged together, where:

0 and 0 are still 0 and 0,

1 and 1 are still 1 and 1,

but 0 and 1 become 1 and 1 (or 0&0)

and 1 and 0 become 1 and 1 (or 0&0).

I remember seeing this wackiness when I bridged two address lines on an EEPROM with the tiniest amount of solder.

RoHS/tin whiskers strikes again?