If you are making a cut, and part of the dirt appears to be missing and you see a different color behind it, there is a hole in your hole. This means that one of the triangles that makes up the face of your excavation wall or floor has been removed by our excavation algorithm.
Below is an example of a hole in the excavation, being evaluated by our developer's excavation debugging tool.
This issue sometimes arises due to rounding errors in the math equations when calculating a operation, usually when it is very close to being parallel with a previous face. If you let us know of any of these issues, we greatly appreciate it! (make sure to duplicate the scenario for us to use, so that the issue is still there when we get it).
You can resolve it by making slight adjustments to your operations. Moving one line in your sketch slightly can usually resolve this issue.