Well, I shoulda asked. Because that was 1 of I think three ways I came up with to get that thick of walls. But I went with your initial call on it being an infill issue.
So it was trying to make the walls 8x.40? 3.2 thick, x2, 6.4 out of 10mm, which what the picture above is showing I'd say. Count the yellow passes.
Sorry man, I should'a spoke up. As far as why it is doing that, I don't know of any other way that would get set like that out side of you inadvertently setting it. IS it possible you were trying to input .80 wall thickness in wrong place? And it took the input as 8?
I have about 75% of all the Cura options turned on now, it can be confusing, I have mistaken input meaning because I was not paying enough attention.
Good to hear your past the issue. I'm about to print my first test gear for an extruder, fingers crossed.