Eryl,
I am having problems with an HP printer, windows 10 and ALL the Affinity programs.
Like you I have no problem printing with other software.
https://forum.affinity.serif.com/index.php?/topic/66262-hp-printer-settings-not-recognised/
I have been trawling through all the posts about printing from Affinity programs and have come to the conclusion that it is a waste of time using the print option in all of them. If you need to print anything then it needs to be exported in a format such as .jpg, .pdf or whatever so your files can be opened in another third party software and printed from that using their print dialog in conjunction with the HP dialog.
I bought Photo and Designer this week based on the website advertising and other reviews without first testing it, silly me. I am a very long term Serif user who is used to suffering workarounds, but this print issue is a deal breaker. The programs are good and will get better but basic printing should be a given at this stage of development. I mean, how can you not have the very basic 6x4 and 7x5 print option for photos. Back to the Plus series for me until improvements are made to the printing process.