It seems that after the recent updates, the pickaxe no longer works. (Confirmed on first two floors, using the miner). Could you take a look into it when you have the time?
Also, a random idea. Right now, once you have the "annihilator" achievement there's no benefit to completely clearing a floor. Would it be possible to add a little cash bonus or bonus item (maybe by having an item chest spawn) for when a floor's been completely cleared?