Mofab

Yes they differ. 300 dpi in Publisher and 72 dpi in Designer. The multiplication shows that there's the bug. Having a Designer document set up in millimeters 72 dpi, then change it to 300 dpi, makes everything shrink. I do not expect that to happen. Again – copying a group AND an ungrouped object at the same time, makes them behave different (ungrouped is fine). (There you have another small ”bug”. DPI refers to print-dots per inch. It should of course be PPI in document settings.)

It doesn't show overprint.

Same bug when copying from Publisher and pasting in Designer, but the line weight gets thicker.

When a grouped object is copied from Designer, it doesn't keep the line weights when pasted in Publisher. Non grouped object are ok. In my example they go from 16 pt to 3,8 pt. (I would also expect global colors to follow along.)

Can you possibly attach the file, so can I take a look.

Is your document color format CMYK?

”Overprint Black” shall be unchecked. Otherwise all black gets overprint.

In the Layers studio or under menu Layer > New Adjustment

I just discovered there's a ”Soft Proof” Adjustment layer. Unfortunately it does not show overprint. I think it should. (feature request)(and it should be in the view menu – not an adjustment layer – that's just awkward)

Also if you have only the slightest percent of other colors, that percentage will have priority over the background.

Maybe it depends on your export settings(?) Choose PDF/X-1a.

So ”Overprint” is set by color swatch (globals). However you also need to uncheck ”Overprint Black” in PDF export settings (the ”More” button), for Affinity to respect my settings completely.

Look up ”Overprinting” in Affinity Publisher Help.

No you don't. You decide on export if it will be converted. PDF can handle both. PDF/x-1a is very strict and keeps nothing as rgb. It's the same in Publisher.

Now you are starting to grasp it Global Layers has not much to do with global contents. Everything on the Layer is unique to the page – except for Master page content, put in the same Layer. They're mostly used for fast switching language, turn on/off comments, sometimes templates that you like to keep on the page instead of on master, and other stuff I can't think of right now. – And that pretty much answered the question that you didn't think I answered. My first post in this thread suggested a way to implement a feature request (global layers) in the existing approach, without needing to make it from scratch. Detach mode is just another approach for altering Master content, than InD's ”Detach master item”. That's fine with me. That wouldn't need to be used that often anyway. Glad to hear the developers are aware of its necessity.