Volume is omitted on book entry types

[wynksaiddestroy]

I want to cite the well-known book "The Art of Computer Programming":

@book{knuth1998,
  title={The Art of Computer Programming},
  subtitle={Sorting and Searching},
  author={Knuth, Donald E.},
  volume={3},
  edition={2},
  publisher={Addison–Wesley},
  isbn={9780201896855},
  year={1998}
}

Unfortunately the volume is omitted in the bibliography:

If I use authoryear instead of iso-authoryear the volume will be there:

I have created a minimal working example. There I tried using both @book and @mvbook entry types.

How can I display the volume? Have I overlooked a configuration option?

Thanks in advance ❤️

[moewew]

The missing volume probably still needs looking at, but for the entry in question it is better to use maintitle+title instead of title+subtitle. Then the volume is shown:

\documentclass[ngerman]{article}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=iso-authoryear, backend=biber]{biblatex}

\begin{filecontents}{\jobname.bib}
@book{knuth1998,
  author    = {Knuth, Donald E.},
  maintitle = {The Art of Computer Programming},
  title     = {Sorting and Searching},
  volume    = {3},
  edition   = {2},
  publisher = {Addison–Wesley},
  isbn      = {9780201896855},
  year      = {1998},
}
\end{filecontents}
\addbibresource{\jobname.bib}

\begin{document}
\cite{knuth1998}
\printbibliography
\end{document}

For future bug reports you may want to keep in mind that it is more convenient to have the minimal working example in the post directly instead of a separate repository. (filecontents can be extremely handy here, because it can make the .tex file self-contained.)

[wynksaiddestroy]

That was easy. Thank you very much!
Thanks for the hint as well. Maybe you should include a short notice in the README.md file on how to report an issue with a minimal working example. So others won't make the mistake as myself.
Should I close the issue or do you want me keep it open?

[moewew]

I think the issue should stay open until someone with access to the standard has checked what should happen with the volume field in case there is no way to use maintitle.

MWE with examples from biblatex-examples.bib. Both volume and volumes field are dropped.

\documentclass[ngerman]{article}
\usepackage[utf8]{inputenc}
\usepackage{babel}
\usepackage{csquotes}

\usepackage[style=iso-authoryear, backend=biber]{biblatex}

\addbibresource{biblatex-examples.bib}

\begin{document}
\cite{matuz:doody,aristotle:rhetoric,vazques-de-parga}
\printbibliography
\end{document}

I also get

Package biblatex Warning: No driver for entry type 'mvbook'.
(biblatex)                Using fallback driver on input line 12.

which probably shouldn't be there. The standard styles have

\DeclareBibliographyAlias{mvbook}{book}

for that.