Now that probably every item that can interact with fireplace has a slot in the fireplace, it seems that inventory of the fireplace is unnecessary as it causes confusion and can alter items to become non intractable.
When you create fireplace but don't light it you can place items in it's inventory. However if you close you inventory view and reopen it those items placed there have become non intractable. Same thing obviously happens when your fireplace is lit with the difference that then items become ruined in short time span.
What is the purpose of the inventory in the first place when it cannot be used to store items, it cannot be used to fuel the fireplace (at least I have not managed to do that) and it basically just consumes items you place there?