Old Bruce

That would be the problem. See the list of supported file types https://affinity.serif.com/en-gb/photo/full-feature-list/

It is technically possible but we need to know how many pages in a signature and how many pages per plate and that is currently missing in Publisher.

I too wish for this, Even better would be different text flows or selections or the whole darn document ranges.

For each selection you need a separate adjustment layer. If you want one area darker and another area lighter you need a 'darker' adjustment layer and a 'lighter' adjustment layer with their own selections.

If it is done it may well be the right way. There are a lot of different ways of doing things, try and find the ones that save you the most labour, "Work with your head, not your back"

Back in olden times pranksters would put a stone/marble/nut in a hubcap (remember those?). Rattles when you drive but is silent when you are idleing/gunning the engine in the shop.

Are you using Paragraph Styles? I would recommend doing so. Set up your "1 and a half" Paragraph style and go to the Spacing section and choose Exactly, the other choices will lead to grief as they are based on individual font's measurements. Choose the height of the type on the page 11 pixels, mm, points whatever you use. Set the line spacing to 11 plus 5.5 pixels, mm, points whatever you use. you can change this 5.5 to more or less to achieve what looks good to you. The term leading is from ancient times when I had to put a strip of lead between the rows of individual lead letters (which then got inked and had paper pressed onto them). I use the term 11 on 12 meaning 11 point type (the size of the letters) in 12 point high rows. Spacing is a much better term than leading.

Not here either. Mac OS 10.14.6

It is hidden rather well, you may also be able to change it in the Text Styles tab if you have applied a Paragraph Style to the text.

While it isn't Studio link you can use the File menu to choose File > Edit in Photo/Designer/Publisher to edit the document in one of the other two.

This is why I always use 'Exact' leading. I will frequently use 11pts on 12. So if you wanted to modify my Paragraph style you would use 11pts on 18 (12*1.5) or 16.5 (11 * 1.5). Let the debate ensue as to what a line's depth is.

I haven't tested this but I bet it is caused by a Swatch of any sort, not just Pantone colours.

It is a Mac thing to do with drawing to the screen.

No, this is a limitation that baffles me.

Works here on Mac 10.14.6 Although there is some odd stuff happening with your file when I open it. I have my cursor frozen for several seconds and then it is quite jerky and sluggish.