Unable to toggle list styling in IE8 when cursor is placed in list

In Firefox and IE7, if I place the cursor in a list item, I am able to toggle the different list styles without issue. 

In IE8, it does not seem to matter where I place the cursor, the list style is not toggled off, and new styles are not toggled on. However, if I highlight the entire list, I am able to toggle the list style. Actually, if I highlight a single character in the list, I can toggle the list style. 
Why `null`?