The Split Item function is not working for me in prerel40.  I tried using the Ctrl+Shift+S shortcut and also the Item > Split Item menu option.  Neither worked.  Instead, a new blank item appears below the item I tried to split, but all the text remains in the source item, and the cursor moves to the beginning of the source item.

 

I also shut down AutoHotKey to see if that would make a difference, but it did not.