I'm trying to recreate the Detect Key spell from Morrowind, but I'm running into a strange problem. Apparently, keys aren't considered part of the inventory? I can't get their amount with the GetItemCount function by using the VendorItemKey keyword, or any other keyword I assign to them. However, other items work fine, like gold or specific weapon types.
What's more, is that GetItemCount(VendorItemKey) works fine on the player. I can't get my head around this.

Did anybody try something similar and might know what is going on here?