The furnace burns the stone out of the crushed stone, but no longer makes the stone a smooth stone. This function used to work, but not now. What is the solution?

Was this stone that you mined some time ago, with a silk touch pick? There were some problems with doing that in 1.12, and it created defective stone blocks that had this problem. Try placing the stone and mining it again with a silk touch pickaxe. If that doesn't solve the problem, comment about how you obtained this stone (if you can remember) and/or see if it works with other freshly mined stone.

I found the bug, it is possible that I mined the stones in this version because there were only a few cradle stones. If I re-mined these stones, everything went fine. Thanks

I experienced this issue yesterday. A work around is not a bug resolution, why is this marked as resolved? Please fix this bug!