As that title says, I smelted some cobblestone into stone. When I finally got a silktouch pickaxe and mined some stone and went back to store it, it doesn't stack with the stone that I smelted from cobblestone.
This however can be fixed by placing down the smelted stone and mining it again with a silktouch pick, but it time consuming and uses some durability on my pick.
Thank you for your report!
However, this issue has been closed as a Duplicate of MCPE-48421.
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