When I create a new outer shadow the colour is shown in CMYK mode with the values C=0 M=0 Y=0 K=100 but when I export the document to PDF I see that this isn't true, because the shadow is rasterized with all 4 CMYK colours. I can fix this simply by going to the colour palette and pressing Enter.
I attached some files:
Document.afdesign is a a test document with the same motive twice: the upper one without pressing Enter first and the bottom one with pressing Enter first.
Screenshot 1.png is what I see in the colour palette for both motives.
Screenshot 2.png ist what I get after exporting the document.
MacOS version: 10.14.6
AffinityDesigner version: 1.10.4
Document.afdesign