I'm working on a board with stacked buried and blind vias. The nc drill files come out fine, but we have a policy of generating drill drawings also, and I'm having problems with them. My board is only four layers, so I have via types 1-2, 2-3, and 3-4. It seems that the drawings for buried vias are correct (1-2 and 3-4), but the blind via drawing is seeing "two drills with different sizes at one point" even though all of the vias are the same size. Then some of the drill locations are dropped off the drawing. I'm not even sure the number of drills in the chart is correct.
What is causing this, and is there a way to fix it?