ASA ironing fail

[martind]

I print from ASA on X1C, ironing set to top surfaces, rectilinear, speed 30, flow 10%, line spacing 0.15mm and inset 0.21 mm. This is what I got (I stopped the print in the middle of the ironing):

The previous layer is great, but the ironing ruins it totally, it makes rough surface with the lines. Why it happens?

[martind]

So I printed some smaller object with ironing, and it printed well. Then I again printed the big object and the ironing failed again.