So: I've created a merchant and gone through all the necessary steps and it will open the shop to sell me items but only what in the NPC's inventory and nothing in the chest that my custom merchant faction links to. I'd guess I'm just missing some small detail or that it's bugged, but I followed the tutorial Making a Merchant over at the CK wiki which has worked fine for me in the past but this time doesn't seem to be working properly. Any ideas as to how to fix this issue?

If your merchant is bound to an object (like a marker) instead of a place, you need to give the faction some range (by default is 0, but that's because by default vendors are bounds to places)

I did try this with no luck, although the merchant itself isn't bound to an object. The faction is set to Near Self and linked to a chest and the NPC is a member of that faction.