% arara: pdflatex: { action: nonstopmode }
% arara: makeglossaries
% arara: pdflatex: { action: nonstopmode }
% arara: pdflatex: { action: nonstopmode }
\documentclass{article}

% WORKING:
% \usepackage[style=alttreehypergroup, symbols, nolong, nosuper, nonumberlist]{glossaries}

% NOT WORKING:
\usepackage[sort=def, style=alttreehypergroup, symbols, nolong, nosuper, nonumberlist]{glossaries}

\glssetwidest[1]{xxxx}
\makeglossaries

\newglossaryentry{firstgroup}{name={firstgroup}, description={\nopostdesc}}
\newglossaryentry{aaa}{name={aaa}, description=abcd, parent=firstgroup}

\newglossaryentry{secondgroup}{name={secondgroup}, description={\nopostdesc}}
\newglossaryentry{bbb}{name={bbb}, description=abcd, parent=secondgroup}

\begin{document}
\glsaddall
\printglossaries
\end{document}