KM 6000L - Gradients don't print - the final 20% Bk just cuts out

[kalinzlatkov]

Any ideas why this gradient won't print?
M 44% + Y 94% to 20% K

I managed to print it - barely - after 20 sheets wasted playing with settings...

At the same time I made a simple radial gradient in InDesign and printed flyers and a business card and it printed perfectly!?

Thanks!

I have the file attached below.