XnView Software

Strange. The good news is that it definitely works on other peoples' systems - so at least you know that it can be done. Did you install AP in the Windows default location? If not, perhaps you could re-install it there. I'm not sure what else to tell you.

If you go to Windows Explorer and double click on a photo (jpg/nef/etc), does the photo automatically open in Affinity? If not, you must set it in Windows first so that will do so (one way to do this is by by searching for "default apps" in the Windows search bar and changing it there).

As noted earlier, you must set your Windows (10/11) default app for opening photos to Affinity Photo 2 to be able to open photos directly from "Open With", "Associated program" (or by clicking F3). Getting the "Associated editor" (F4) to work properly is entirely different matter - because I'm ...