Issue with glossary page numbers

Question

I am using lualatex and I have an issue where the page numbers in my glossary would sometimes appear on a seperate line, like in the picture below. How can I prevent this?

UPDATE

I think I have it boiled down to this combination of settings for scrbook, which are set in a custom documentclass provided by our institute. So the question that remains is what is happening and how can I prevent this?

\documentclass[%
    fontsize=12pt,
    DIV=13,
    BCOR=8mm
]{scrbook}


% use glossaries and acronyms
\usepackage[indexonlyfirst]{glossaries}
% display glossary entries emphasized
\renewcommand*{\glsentryfmt}{\emph{\glsgenentryfmt}}
% dots between glossary description and page number
\renewcommand*\glspostdescription{\dotfill}

\newglossaryentry{pubmed}{
    name={Entrez PubMed},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf }
}


\makeglossaries
\begin{document}
\printglossaries

The \gls{pubmed} is awesome.

\end{document}

Answer 1

Your \dotfill command is the cause for the phenomenon: it doesn't ensure a line break is not taken after it.

However, you want to set a minimum number of dots, besides avoiding the break.

\documentclass[%
    fontsize=12pt,
    DIV=13,
    BCOR=8mm
]{scrbook}


% use glossaries and acronyms
\usepackage[indexonlyfirst]{glossaries}
% display glossary entries emphasized
\renewcommand*{\glsentryfmt}{\emph{\glsgenentryfmt}}
% dots between glossary description and page number
\renewcommand*\glspostdescription{\mindotfill}
\makeatletter
\newcommand{\mindotfill}{%
  \leavevmode % switch to horizontal mode
  \penalty\z@ % possibly break here
  \mbox{}\nolinebreak % don't remove the leaders at the start of the line
  \cleaders\hb@xt@.44em{\hss.\hss}\hskip 1.5em plus 1fill % fill with dots, at least 3
  \kern\z@ % don't remove the leaders at a break
  \nolinebreak % don't break here
}
\makeatother

\newglossaryentry{pubmed}{
    name={Entrez PubMed},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf}
}
\newglossaryentry{pubmed1}{
    name={Entrez PubMed1},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf 
        fasfasf fasfasf}
}
\newglossaryentry{pubmed2}{
    name={Entrez PubMed2},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf
        fasfasf fasfasf fasfsase}
}
\newglossaryentry{pubmed3}{
    name={Entrez PubMed3},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf
        fasfasf fasfasf fasfsasee}
}


\makeglossaries
\begin{document}
\printglossaries

The \gls{pubmed} is awesome. Also \gls{pubmed1}, \gls{pubmed2} and \gls{pubmed3}.

\end{document}

Answer 2

Until a proper answer comes, here is a hack. Put

\renewcommand*\glspostdescription{\dotfill\kern1ex}

Change 1ex suitably.

\documentclass[%
    fontsize=12pt,
    DIV=13,
    BCOR=8mm
]{scrbook}


% use glossaries and acronyms
\usepackage[indexonlyfirst]{glossaries}
% display glossary entries emphasized
\renewcommand*{\glsentryfmt}{\emph{\glsgenentryfmt}}
% dots between glossary description and page number
\renewcommand*\glspostdescription{\dotfill\kern1ex}

\newglossaryentry{pubmed}{
    name={Entrez PubMed},
    description={is a database of references and abstracts on life sciences
        and biomedical topics hosted by the NCBI affs fasjflkasjflajf fasfasf }
}


\makeglossaries
\begin{document}
\printglossaries

The \gls{pubmed} is awesome.

\end{document}