Game is pretty fun and I found it nice to just brainlessly grinding and exploring but.. I cant find the resource uncommon cube I don't know whether you have to use the compactor or expander or even find it. I've unlocked the fourth floor but deliberately held back to try to find, without success. It's very confusing (to me at least).
Some resources you can find only when the furnace has been turned off for some minutes.
There's also a setting in pause menu -> "Gameplay" -> "Toggle Spooky Stuff" or something like that, if you want to harvest in peace with the furnace turned off.
I do get it though, it is a bit confusing how it works right now, I'll try to make more clear for the next update.