I've had a problem where I've bought out Warmaiden's stocks of smithing supplies, forgot something and reloaded.
The file loads, the inventory only has what I left before loading.

Clearing the Xbox 360 cache seems to have reset this issue. It seems like the information on inventory is being stored in the cache and not related to the save file.
So the cache is static and though the save state is loaded to a previous state, the cache doesn't change to represent the change in the game timeline.