If you choose to place torches with the exchanger, the torches are not placed but instantly drop (don't replace the block) and no torches are consumed in your inventory. It hapened to me with the obsidian exchanger, don't know if the bug is for all exchangers ...

That's weird, will have a look into that when I can.

Okey, good luck !

Should be fixed in 2.7.2, let me know if it's not working!