When I click "Add a hole", the screen turns green. When I move the mouse around, I can see a VERY large hole in the green flying around opposite to the mouse movements. Clicking just makes the green go away.
I have already hollowed the model. 1.8mm wall thickness. I set the hole diameter to 2mm and the depth to 1.8mm. Windows 7 64 bit, 16G ram in a Panasonic Toughbook CF-53, 64 bit version of ChiTuBox.