Better late than never... Thank you Lee. My apologies too since I didn't even know the response was there until now.
Before I saw this response from you I had resolved the bleed issue. I'm not 100% sure what I did now, but certainly I was able to press on with the document. I did get another issue though which may be related to what you describe. I was considering raising a new topic, but let's see if you have any feedback to this before I do that, just in case it is related.....
When I see the images (on PC screen) in Affinity Photo they always have good contrast and the blacks are well defined (They are TIFF B&W images).
When I insert the images (as TIFF) into Affinity Publisher for document editing, they change to have slightly less contrast and the blacks are not so deep.
When I exported to PDF (CMYK profile), and open that on my screen, the contrast is good again and the blacks well defined. The PDF was sent off to the printer who required CMYK.
When I received the printed result back from the printers the images have less contrast and the blacks are not so deep, and actually very close to that of the Publisher output during editing on the screen.
I have the feeling this is to do with my colour space settings (even though the affected ones are B&W) through the system process. My knowledge of colour space setting is not good, but the print company suggested to use PDF/X-1a for the export, and GRACol 2006 Coated for the colour profile. The latter does not seem to exist in the selections.... If I am in fact looking in the correct place.
Do you have any suggestions please?
Best regards,
G.