拖放后，Java List停止更新

I am creating an application that converts files from xml to pptx. The user will drag items from a JTree to a JList to create the slide. I have managed to get everything working but the JList seems to disappear after the drop. I know the drop is received because of print statements, and that it's not null. The JList is still there I believe, because I can print the items in the array. Through testing, I think that something is wrong in the custom DefaultListModel I have created. It is not calling an update/redraw/revalidate after the drop for some reason, or has released its action listeners because I notice that the getSize and getElementAt methods stop getting called after the drop. It does however draw correctly if I add items to the ListModel on app init.I am creating an application that converts file