With such an old controller, is it possible that the North-South panel switch got knocked down from its correct position, or acquired debris or corrosion over such a long time of not being toggled, probably never?
Just as shot in the dark, I would flip the N-S panel switch a few times to clean its contacts, then set it right.
Having checked all the correct keypad settings, most likely are the common problem many have, even with newer CPx’s, of a drained keypad battery, resulting in a corrupted star internal database.
Both are easily fixed with a new coin battery and/or a database download. The latter should be tried first, since it is easier and quicker than dismantling the keypad for the battery. It doesn’t take much of a dropped voltage from its standard 3 vdc to begin acting erratically. I just changed a “key-fob” battery, and the meter read 2.99 volts, so you would assume it would be fully charged. Meanwhile the fresh replacement battery read 3.5 volts. Such a marginal difference makes operations erratic.
Wouldn’t it be nice if the next CPx model had a “coin battery slot”, pushed in from the side, like some cameras do? Sure would save the risk of snagged internal wires, and broken fibre optics (key-light) strands, when just replacing the battery.