Spot colour on non-print layer will appear in separations as CMYK
Setup a spot colour
Apply it to any object
Set your layer to no printing
Check the separations
It shows the spot colour as CMYK.
Until you set the layer to Print again.
Eugene, Ton -
I still can't replicate this, even with a fresh document. Doesn't affect my installation at all whether the spot color is custom, or pantone. I did briefly see the object flicker back to visible but it didn't stay visible. Looked like a slight lag in the rendering.
Am I missing something?
*** edit, leaving above for posterity ***
I incorrectly assumed "non printing" meant "hide the layer" or "layer visibility turned off" rather than set the layer's properties/options to be a non-printing layer.
It didn't initially cross my mind to try that because that's an option that I knew of but have never used for any reason.
Easily reproduced using that option. Agree that it's very strange and probably unintended behavior.
Eugene Tyson commented
I created a thread here and had it confirmed
I am unable to reproduce this in my Illustrator installation.