I've been testing under town, plot land where no one has rights(but I'm not the 1 who destroyed parts of trader joe's shop).
this also seems to work with small logs, planks, marble sheets, small granite, medium granite, copper sheets, silver sheets, and iron sheets. I haven't done the whole grind thing so I don't have steel or zircon sheets to test. also I've carved a path across plot land with tiny granite...
I remember a similar glitch many years ago on 1 of Gary's servers and he seemed to fix it easily enough after I pointed it out, so you could probably ask him if you're not sure what the problem is.