I've created a simple model that has a pair of 9mm diameter bores through the part (it's a handle designed to hold 2 electrodes for a battery spot welder); the model shows the bores as clear, and Creality Slicer shows the bores as expected, but the part printed out with the bores filled, although there is evidence of the bore edges on the faces. The modelling was done in DesignSpark mechanical and run through Creality Slicer and printed on my Ender 3. Has anyone seen this behaviour before?