I'm using all latest versions as of now, I believe:
- RStudio-2022.06.0-daily-410.exe
- quarto-0.9.415-win.msi
- Zotero 6.0.7 Windows standalone software
quarto does not see all references in a Zotero folder.
Here's what's in my Zotero folder ("dummy"):

Here's what I get when I use the insert-citation dialog:

You can see that one of the Ron Snell citations does not show.
I am not sure what distinguishes it. However, I created it by hand rather than saving it to the Zotero library through a browser (Chrome) web extension.
The problem does not seem to be on the Zotero end. Here is what I get if I export the dummy subcollection:

It is clearly there in the exported .bib file.