Originally posted by ChinoValley:

Ignore the mod, it's not the issue. Dig depth is capped so if you're mining on a slope, and dig down to the deepest level possible, you will also create a slop--just deeper down than the original slope. If you're going to dig down to the deepest level, then start at the TOP of your slope and dig down. Once you find the bottom (where you can't dig further), then dig outward to create the level space. Level it based on digging down from the HIGHEST point, not the LOWEST point of your slope. That might help.

Thank you very much. I didn't know that dig depth worked that way so I will try that instead for my next nodes. I was doing literally the exact opposite, starting at the lowest point of the slope and then trying to even it across.