The reset is done using the frame's document, via doc.close() and doc.open(). This clears the annotation pane OK, but the open() causes a History record to be created.
This is compounded by the fact that a word may be covered by many annotations, and there's one of these clear actions for each covered annotation. So if you have 6, moving out causes 6 resets, and 6 additions to the History. This rapidly make it appear that the "back" button is broken...
Use a different reset method to avoid overloading the history list.