I can confirm this behavior with 1.17.2 on Windows. It’s not limited to the Neutral profile. I didn’t try with anything but an area mask, but with an area mask (at least) if “Show mask” is enabled, I get the mask in the output. Looks just like the preview except it’s full size.
I may misunderstand, but I don’t think it’s supposed to do that.
To be honest, I don’t remember whether it is intentional or not
I do remember thinking about this, as this behaviour is a hack that allows you to sort of export a mask generated in art to use it in another app like gimp. However, I am not so sure it’s actually that useful, as the mask is obviously not directly usable and would need quite a bit of processing.
Bottom line, I’ll take another look and maybe change the behaviour. Thanks for pointing this out!