Sorry, but that looks exactly like a dying slot.
The range line shows the RAM size for each slot. And the first one shows only 000.....


Edit (I was in a hurry and had only my mobile to answer):

To be more precise, the range lines gives start and end addresses for each RAM module found. 0 - 0 means no address range for slot0 (the lower one, called factory slot). I don't know how Open Firmware detects the RAM sizes, but I would guess with some kind of read/write tests to certain addresses. If everything went well the Apple Chime will sound during startup. If you don't hear anything, something is fishy.

Regarding the RAM slot, my theory is that there is some kind of soldering issue or an issue with the slot itself. It seems that the SPD can always be read out, but the size check fails. So maybe address lines and/or data lines are affected. Apple didn't care about that, they simply replaced the logic boards back in the days.
You can also override the range line in OF, but this will most likely crash MorphOS or the HW test when accessing the RAM module.
Why OS X sees more RAM is strange, with my defective PowerBook OS X also ignores the lower RAM module. So try to load up some memory intensive things in OS X and see if it is crashing...