strange behaviour with glossaries see key

Question

I have been baffled by exactly how to use the see key of the glossaries package.

Section 8 of the manual writes:

Note that in this case, the entry with the see key will automatically be added to the glossary, but the cross-referenced entry won’t.

Contrary to what the manual says, specifying a see key does not add the automatically add the entry to the glossaries as my MWE shows. I got one of the entry to show up by using \glssee within the description key, but it fails to generate the text see also. I can manually write the cross-reference within the description key, but I am curious as to why the see key doesn't seem to do what the manual says. What gives?

\usepackage[notree,shortcuts]{glossaries}

\newglossaryentry{Blackbox}
{
  name=Blackbox models,
  sort=blackbox,
  description={--- In system identification, the term \emph{blackbox} modelling refers to the process of modelling a system through non-parametric techniques, without knowledge of physical inner workings of the system, resulting in an \emph{empirical} model}
}
\newglossaryentry{Whitebox}
{
  name=Whitebox models,
  sort=whitebox,
  description={--- In system identification, the term \emph{whitebox} modelling refers to the process of modelling a system through first principles, laws of physics and explicit assumed relationships between the input and output through prior knowledge of the system, resulting in a \emph{mechanistic} model}
}
\newglossaryentry{Mechanistic}
{
  name=Mechanistic models,
  sort=mechanistic,
  description={},
  see=[see also]{Whitebox},
  nonumberlist
}
\newglossaryentry{Empirical}
{
  name=Empirical models,
  sort=empirical,
  description={\glssee[see also]{Empirical}{Blackbox}},
  see=[see also]{Blackbox},
  nonumberlist
}
\makeglossaries

\begin{document}
Something about \gls{Blackbox} and \gls{Whitebox}
\newpage
\printglossary[title={Glossaries}]
\end{document}

Answer 1

1. To make a cross-referencing item appear even without citing it, it needs a chance to be written to the glossary, so put \makeglossaries before the entry definition.

2. The \glssee is to be used outside of the actual definitions. The following works:

   \documentclass{article}
   
   \usepackage[notree,shortcuts]{glossaries}
   \makeglossaries         %% Put that here, so entries can be written to the glossary
   
   \newglossaryentry{Blackbox}
   {
     name=Blackbox models,
     sort=blackbox,
     description={--- In system identification, the term \emph{blackbox} modelling refers to the process of modelling a system through non-parametric techniques, without knowledge of physical inner workings of the system, resulting in an \emph{empirical} model}
   }
   \newglossaryentry{Empirical}
   {
     name=Empirical models,
     sort=empirical,
     description={Empirical descr},
     see=[see also]{Blackbox},
     nonumberlist
   }
   
   %\glssee[see also]{Empirical}{Blackbox} %% We need that to include Empirical when just citing Blackbox; or use the 'see' key in Empirical; put it after \makeglossaries and the entry definitions
   
   \begin{document}
   
   Something about \gls{Blackbox}
   
   
   \newpage
   \printglossary[title={Glossaries}]
   \end{document}
   

   In this case, both Empirical and Blackbox show up. Alternatively, use the \glssee instead of the see key in Empirical.