Nightdawg wrote:Try holding soil in your hand and shift+right click close to the green square in your screenshot. DO IT OFF A HORSE, just to have the smallest possible collision box, so you can actually fit in there.
Cave cliffs are super weird, but you should be able to level that particular part up since you were able to dig it down.
Unfortunately, I only get the "there's not enough clearance here" notice. If I'm remembering correctly, there was an update between when I dug it down and I tried to fill it. This terraforming project has been something I worked on on and off over the past several months.