Yeah I was building something that used a bunch of repetitive pieces, so I started copy pasting stuff.... lots of weird things happened. Several times I'd get the wrong altitudes. I'd specify 12, but get 2.4 or -9. Or... a null value. Not a number at all, not even 0. Objects with a null value for y display the value of the last object you looked at with a y value. When you preview, the null value is treated as 0. But it's not displayed as 0 in the editor.