I don't know if restocking is a bug.. but it's money exchange definitely is. No matter how much money it has it will not trade most of it back.

Ah, that's interesting: just looked at Contreras and he is set up the same way: no merchant container is assigned to him, instead he uses a hidden chest in the same cell to store his goods. I guess this is the source of the problem. I was looking at a script attached to the chest belonging to the SCIU which said that there were known problems with vendors not using caps that were stored in their goods chest.

I guess the only real solution is to make the SCIU a proper NPC or creature so it can be assigned a merchant container in the same way as the other vendors who work properly!

It's possible: that's a long-standing "feature" that goes back at least as far as Morrowind. It was largely fixed in Oblivion, I guess as part of the specific "merchant container" mechanism that stops them simply putting goods in their inventory and then equipping them, but there were one or two problem merchants there too, such as Rindir, who'd endlessly store everything in his personal inventory, become over-encumbered and not be able to move, for example.

Again, Dr. Kemp has no merchant container assigned but uses a hidden vendor chest near to his location, so this definitely sounds like it's the common problem with Contreras, Kemp and the SCIU.


Edit: just to be clear (well, inasmuch as my explanations are ever clear!), a "merchant container" is a specific chest or other container that's specified in the NPC's attributes for the purpose of buying and selling, and is often in an entirely different location; what I'm referring to as a "vendor chest" or whatever is just an ordinary container that lives in the same area but is hidden from view, normally by locating it under the floor, which apart from being owned by the NPC has no special attributes. It would appear that the merchant container has a special mechanism whereby any goods that are bought and sold go straight to/from it, bypassing the merchant's inventory, whereas the vendor chest is in essence an extension of their own inventory. I think the latter is a bit of a hold-over from the way merchants used to work, but compared to the merchant container it seems to cause more problems than it solves.

it doesnt restock everything or the total amount of caps. the only thing that it restocks for me is the primer and powder packs, sonic emmiter, and the mods. ive sold it a ton of weapons (i dont get the caps for them cause mines bugged like that) and the weapons dont vanish