It appears that forum users (other than the moderators) do not have the ability to attach files. I've tried in the past to get this fixed (to no avail).
Instead you can send me the kpx file to firstname.lastname@example.org. It would also be helpful to have a PDF that contains the grays that are causing the problem (if the PDF contains sensitive customer information I understand not sending it).
I have updated FFC to 126.96.36.199 and I am still experiencing the same issue even with Convert to CMYK, keep spot colors (Coated FOGRA39).kfp.
Though I have noticed it happens with only some grays, not all.
Please tell me how I can upload to you the KFP file and a PDF file to test. I cannot see an option to attach files on here.
I cannot find the Convert color to 4c for digital printing fixup on my version of Acrobat Pro. Could you add the fixup to the issue? When I run Convert to CMYK, keep spot colors (Coated FOGRA39).kfp, my CMYK grays are converted to CMYK grays (not K only). I am using FFCore 188.8.131.52.
There is a preflight fixup in Acrobat called Convert color to 4c for digital printing. When I use this in Acrobat to convert RGB to CMYK, it works as expected - 4 colour grays are retained, but if I use this profile in FFC it treats all grays as a black only grays and just provides a percentage of K.
Why is this happening? How can a have this work in FFC as it does in Acrobat?