XSIM 练习标题问题

Question

如果我使用 XSIM 包创建第一个练习，并带有特定的副标题，则所有内容都会正确排版。但是，当练习的主体更改为另一个没有副标题的练习时，旧的副标题仍然存在，而它不应该显示。你知道为什么吗？

平均能量损失

\documentclass[oneside]{scrbook}

\usepackage{xcolor,lipsum,hyperref}
\usepackage[use-files,blank,clear-aux]{xsim}
%
\DeclareExerciseHeadingTemplate{custom}{\XSIMtranslate{default-heading}}
%
\DeclareExerciseEnvironmentTemplate{custom}
  {%
    \IfExistSolutionTF
        {%
            \IfInsideSolutionTF
              {%
              \label{sol:\ExerciseID}
              }
              {%
              \label{ex:\ExerciseID}
              }
         }{}%
    \IfInsideSolutionTF
        {%
            {\color{green}\bfseries\XSIMmixedcase{\GetExerciseName}~(\GetExerciseParameter{exercise-name}%
                ~\GetExerciseProperty{counter})}%
        }
        {%
            {\color{orange}\bfseries\XSIMmixedcase{\GetExerciseName}~\GetExerciseProperty{counter}}~{\color{black}\bfseries\itshape\GetExercisePropertyT{subtitle}{\PropertyValue}}%
        }
    \IfExistSolutionTF
        {%
        \IfInsideSolutionTF
             {%
              {\color{gray}\footnotesize{\big(Énoncé:\pageref{ex:\ExerciseID}\big)}~}%
             }
             {%
             {\color{gray}\footnotesize{\big(Solution:\pageref{sol:\ExerciseID}\big)}~}
             }%
         }%
         {}%
  }{}

% Traductions
\DeclareExerciseType{exercice}{
    exercise-env      = exo ,
    solution-env      = sol ,
    exercise-name     = \XSIMtranslate{exercise} ,
    exercises-name    = \XSIMtranslate{exercises} ,
    solution-name     = \XSIMtranslate{solution} ,
    solutions-name    = \XSIMtranslate{solutions} ,
    exercise-template = custom ,
    solution-template = custom ,
    exercise-heading  = custom ,
    solution-heading  = custom
}
%
\xsimsetup{
    print-solutions/headings-template = custom ,
    print-solutions/headings = false ,
}

%
\begin{document}

\chapter{First chapter}

% First typesetting :
%\begin{exo}[subtitle={Test}]
%\lipsum[1]
%\end{exo}

\begin{exo}
\lipsum[1]
\end{exo}

\begin{sol}
\lipsum[1]
\end{sol}

\printsolutions*

\end{document}