Great start to the tutorial. I am not sure what is interfering with the grease cut operation, It is often creating a cut on the inside of the object and then failing to select one side or the other and just sticking to the cut itself. It randomly works, then it stops working again. I have attempted ortho mode, perspective mode, sticking the pencil to the object vs. scene, purging all previous pen marks, deleting the object and starting over. I have no clue what is triggering it to select the cut itself instead of the separated side..