I'm doing my first 4 layer board (1,2+15,16). I originally drew a 2 layer board as a 'top' and 'bottom' I am now trying to make what was the 2 layer bottom to layer 2 in the 4 layer version, just under the 'top' layer. As I 'change' the original layer of what was the bottom layer in the 2 layer design, the vias are disappearing that connected the original 'top' to 'bottom'. Any suggestions?
