So for this bug you input items into a smelter possibly really anything fueled. But smelter. As the items almost finished smelting you remove the stack had better results doing it in realms and onto another stack of the smelted item. Though works on any empty slot to then the game awards xp and puts the ore back where it was. Similar to the old bug where you just took a item from a smelter and put it onto a full stack of it. Oh a question this missed I use the touch interface haven't tested this but found some things only work with the touch. Message me back if this  make sense and I'll upload a video of me doing it