Seems like you are always having issues. I use this on my main and have zero problems. Post a log so handnavi can look at it. My guess would be you have it set to only use on bosses and you're attacking adds or some crap. Could be wrong but no one knows until you post a log.
No , for example i have the soul capitor trinket and want to burst at start if really sucks 90% of the time you press the burst button = bersek + potion + incarnation = 90% incarnation dont pops and you have to turn the toon away from boss and keep spamming since framelock spams buttons , the other thing it sux its he keeps targeting mobs not at front to cast moonfire ( socretar fight and even archimonde and others ) , this cant be only me , and other CR this dont happens ( at least the incarnation thing ) , the rest its fine.
I just made a new log just for this on a dummy , check it out.
I even spammed the burst key > mouse clicked > dont works unless i clear target or turn away from target.
As you see on the log i pressed ALOT and still nothing.
On the other i click burst wait a bit so i wait for start rotation but even on that bersek +potion its up already > incarnation NEVER
Even doing a macro
#showtooltip Incarnation: King of the Jungle(Talent, Shapeshift)
/cast Incarnation: King of the Jungle(Talent, Shapeshift)
/cast Tiger's fury
/cast Berserk
/use Draenic Agility Potion
I can spam > click on it as long as i want it wont use incarnation AFTER combat > framelock spam button too much