Smooth Stone cannot be created in a furnace using Stone.
Steps to recreate:
Place a furnace
Place fuel in furnace and smelt cobblestone into stone
Place stone into furnace to be smelted into smooth stone
Observed result:
Nothing happens
Expected Result:
Stone should be smelted into smooth stone
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Comments

Couldn't reproduce.

If you couldnt reproduce then its because you are not opted-in to the beta version of minecraft from xbox one which is currently 1.13.0.1 because I can absolutely confirm it is impossible to turn stone into smooth stone. Not cobblestone to stone.
Thank you for your report. However this issue has already been reported as MCPE-47907. If you have anything to add to the conversation comment there. Also, please search for an issue before creating a ticket for it. Have a great day! 🙂