In class TMFNCGanttClasses a new member variable TTMSFNCGanttTask.FUpdateList was introduced with version 1.2.3.4. Loading several projects consecutively into the Gantt chart leads to an exception at some point.
We were able to fix the exception by doing a FreeAndNil(FUpdateList) instead of a FUpdateList.Free in TTMSFNCGanttTask.Destroy and adding the check Assigned(FUpdateList) before accessing FUpdateList in TTMSFNCGanttTask.AddToTaskUpdateList and TTMSFNCGanttTask.RemoveFromTaskUpdateList.
Thank you for letting us know, we added the fixes and it will be available in the next release of TMS FNC Gantt Chart.