"Manuscript submitted for publication" with APA BibLaTeX style

Question

I use Zotero with Better BibTeX to manage my references. I am trying to reference an article that has been submitted for publication. According to the APA style guide, the manuscript should be cited with year it was written, and listed in the references with "Manuscript submitted for publication" at the end of the reference.

I have tried to follow the instructions in section 4.2.1 of the APA BibLaTeX style documentation, but either I am doing something wrong or it doesn't work. Adding pubstate = {mansub} to the bib entry correctly displays "Manuscript submitted for publication" at the end of the reference. However if I also give the year, then "Manuscript submitted for publication" is omitted from the reference.

MWE:

main.tex

\documentclass{article}
\usepackage[american]{babel}
\usepackage{hyperref}
\usepackage{csquotes}
\usepackage[backend=biber, style=apa]{biblatex}
\addbibresource{references.bib}
\DeclareLanguageMapping{american}{english-apa}


\begin{document}

\section{Introduction}
\cite{matherIntraplateVolcanismTriggered2020}

\printbibliography
\end{document}

references.bib

@article{matherIntraplateVolcanismTriggered2020,
  title = {Intraplate Volcanism Triggered by Bursts in Slab Flux},
  author = {Mather, Ben R. and Müller, R. Dietmar and Seton, Maria and Ruttor, Saskia and Nebel, Oliver and Mortimer, Nick},
  date = {2020-12-16},
  journaltitle = {Science Advances},
  volume = {6},
  number = {51},
  pages = {eabd0953},
  pubstate = {mansub},
  publisher = {{American Association for the Advancement of Science}},
}

Answer 1

pubstate is available as an alternative to supplying a year in citations and bibliography, manuscript submitted is not appearing as an additional item in the bibliography entry but in place of the year. If a year is available that is used and so pubstate is suppressed.

Instead the howpublished field also supports mansub and adds an additional item in the bibliography entry indicating that the manuscript has been submitted for publication.

\begin{filecontents}{\jobname.bib}
@unpublished{a,
  title = {Title},
  author = {Author, A.},
  journaltitle = {Journal},
  date = {2023},
  pubstate = {mansub},
  howpublished = {mansub},
}
@unpublished{b,
  title = {Title},
  author = {Buthor, B.},
  date = {2023},
  howpublished = {mansub},
}
@unpublished{c,
  title = {Title},
  author = {Cuthor, C.},
  howpublished = {mansub},
  pubstate = {mansub},
}
@unpublished{d,
  title = {Title},
  author = {Duthor, D.},
  pubstate = {mansub},
}
@unpublished{e,
  title = {Title},
  author = {Euthor, E.},
  howpublished = {mansub},
}
\end{filecontents}

\documentclass{article}
\usepackage[american]{babel}
\usepackage{hyperref}
\usepackage{csquotes}
\usepackage[backend=biber, style=apa]{biblatex}
\addbibresource{\jobname.bib}

\begin{document}
\cite{a,b,c,d,e}

\printbibliography
\end{document}

Author, 2023; Buthor, 2023; Cuthor, manuscript submitted for publication; Duthor, manuscript submitted for publication; Euthor, n.d.

References

Author, A. (2023). Title [Manuscript submitted for publication].

Buthor, B. (2023). Title [Manuscript submitted for publication].

Cuthor, C. (manuscript submitted for publication). Title [Manuscript submitted

for publication].

Duthor, D. (manuscript submitted for publication). Title.

Euthor, E. (n.d.). Title [Manuscript submitted for publication].

Note while this all carries over to @article, you most likely want to be using @unpublished (in Zotero this would mean setting Item Type to Manuscript rather than Journal Article) which doesn't expect a journaltitle.