type //unload spellcast and see if it work, if so, yeah it's an xml problem, cancel mostly.
Something like that:
Code
<if spell="Utsusemi: Ichi" NotBuffActive="Silence|Mute|Omerta|Obliviscence">
<action type="midcastdelay" delay="2.7" />
<command when="midcast">cancel 66</command>
</if>
if utsusemi is instant, it will wipe shadow after 2.7s casting (it's only count the start casting, precast), that's why shadow disapear.
I dont know if there's a way to <cancelspell /> the cancel plugin if not casting.