Tabu Search实现考试排程时重复触发同一约束失败求助

我实现了类似考试排程的系统，Exam类与Rooms、Teachers为两个ManyToMany关联。采用Tabu Search测试两门课程的小案例时，尽管其他教室和教师仍有空余，求解器始终触发同一约束失败，且故障始终针对相同课程。即使在求解前清空所有数据，似乎仍存在解决方案缓存的情况。此外，查看输出日志发现存在比最终方案得分更优的解，但Tabu Search未选用该方案。请问是否有开发者遇到过类似情况？

求解器配置代码 #

<solver>
  <!--<moveThreadCount>AUTO</moveThreadCount>--><!-- To solve faster by saturating multiple CPU cores -->

  <!--moveThreadCount>AUTO</moveThreadCount-->

  <solutionClass>org.acme.timetabling.domain.ExameTable</solutionClass>
  <entityClass>org.acme.timetabling.domain.Exame</entityClass>
  <entityClass>org.acme.timetabling.domain.docente.Docente_Assignment</entityClass>
  <entityClass>org.acme.timetabling.domain.sala.Sala_Assignment</entityClass>

  <scoreDirectorFactory>
    <constraintProviderClass>org.acme.timetabling.solver.ExameTableConstraintProvider</constraintProviderClass>
    <initializingScoreTrend>ONLY_DOWN</initializingScoreTrend>
    <!--<scoreDrl>org/acme/timetabling/solver/ExameTableDrolls.drl</scoreDrl>-->
  </scoreDirectorFactory>

  <!--<termination>-->
    <!--<minutesSpentLimit>1</minutesSpentLimit>-->
  <!--</termination>-->
  <!-- Tabu Search performs much better than Late Acceptance (default algo) on this use case -->
<!--  <constructionHeuristic>-->
<!--    <constructionHeuristicType>FIRST_FIT</constructionHeuristicType>-->
<!--  </constructionHeuristic>-->

  <constructionHeuristic>
    <queuedEntityPlacer>
      <entitySelector id="placerEntitySelector">
        <cacheType>PHASE</cacheType>
        <entityClass>org.acme.timetabling.domain.Exame</entityClass>
      </entitySelector>
      <changeMoveSelector>
        <entitySelector mimicSelectorRef="placerEntitySelector"/>
      </changeMoveSelector>
    </queuedEntityPlacer>
  </constructionHeuristic>
  <localSearch><localSearchType>TABU_SEARCH</localSearchType></localSearch>
</solver>

内容的提问来源于stack exchange，提问作者Ricardo Miguel