I've been trying to dig further down into the Shade's home with the mattock, but once I've done the floor where the bed is meant to go, it seems to stop digging on the second staircase down towards the mushrooms.

Is this a glitch, or is it something I'm missing? The option to use the mattock comes up, but clicking on it, or where I want to dig doesn't make the shade dig further. Please, is there a solution to this? Anyone else had this issue?