Multiple citations in apacite with natbibapa option result in appending ",1"

Question

I want to cite as "Simpson and Bouvier (2011, 2014a,b)" or "Simpson and Bouvier (2011, 2014a, 2014b)", but with apacite and the natbibapa option I am obtaining "Simpson and Bouvier (2011,1,1)". How to change this?

The MWE:

\documentclass[oneside,11pt]{article}

\usepackage[hidelinks]{hyperref}
\usepackage[natbibapa]{apacite}

\begin{document}

Got: Simpson and Bouvier (2011,1,1) using \cite{Simpson2011, Simpson2014, Simpson2014a}\\

Desired: Simpson and Bouvier (2011, 2014a,b) or Simpson and Bouvier (2011, 2014a, 2014b)

\begin{thebibliography}{3}

\bibitem[Simpson and Bouvier, 2011]{Simpson2011}
Simpson, H. and Bouvier, M. (2011).
\newblock Title 2011.
\newblock {\em Journal}, vol(num):pages.

\bibitem[Simpson and Bouvier, 2014a]{Simpson2014}
Simpson, H. and Bouvier, M. (2014a).
\newblock Title 2014a.
\newblock {\em Journal}, vol(num):pages.

\bibitem[Simpson and Bouvier, 2014b]{Simpson2014a}
Simpson, H. and Bouvier, B. (2014b).
\newblock Title 2014b.
\newblock {\em Journal}, vol(num):pages.

\end{thebibliography}

\end{document}

Answer 1

(too long for a comment, hence posted as an answer)

I am puzzled by your claim that \citet produces a citation call-out of the form "Simpson and Bouvier (2011,1,1)" -- at least if the supposition is that the entries in your thebibliography environment were created with the help of the apacite package and its eponymous bibliography style, viz., apacite.

For sure, if I create a small test bib file with three entries and a test LaTeX document that employs the apacite package and the apacite bibliography style, \citet generates a call-out that's precisely in one of the two formats you have declared to be acceptable.

\documentclass[11pt]{article}

\begin{filecontents}[overwrite]{mybib.bib}
@misc{Simpson2011, author="H. Simpson and M. Bouvier", year=2011, title="Thoughts {A}",}
@misc{Simpson2014a,author="H. Simpson and M. Bouvier", year=2014, title="Thoughts {B}",}
@misc{Simpson2014b,author="H. Simpson and M. Bouvier", year=2014, title="Thoughts {C}",}
\end{filecontents}

\usepackage[natbibapa]{apacite}
\bibliographystyle{apacite}
\usepackage[hidelinks]{hyperref} % load 'hyperref' last

\begin{document}
Desired: Simpson and Bouvier (2011, 2014a, 2014b)

\verb+\citet+: \citet{Simpson2011,Simpson2014a, Simpson2014b} 
\bibliography{mybib}
\end{document}