Tall legends, especially on large page sizes, may change size when the map is opened.
The map was saved with the ArcMap window maximized and then opened with the window not maximized, or vice-versa.
Solution or Workaround
- If the ArcMap application window is maximized, open the map with the window not maximized.
- If the ArcMap application window is not maximized, open the map with the window maximized.
- If neither of the above solutions work resize the legend after opening the map.