[21:41:25] You cannot dig in such terrain. I have this same issue. I created a 3x5 tile grid with floor boards. I started digging in one corner, no problem. Then I tried digging in another corner (and then again in every other possible corner) inside the grid, and I could not. I could dig on every tile on the outside of the griid. I then destroyed one floor board in the middle of the grid and was able to dig down the 3 of the 4 corners of that tile. Definitely something wrong.