How does Battle Cry actually work? Does the 100% crit chance guarantee a crit? I ask because I've been trying to figure out what I'm doing wrong to boost my DPS and noticed today, multiple times, while working on the Raid dummy I was not enraging when I expected to due to Battle Cry being up. 
 
I created a short clip that shows this happening:  
 
 
Is this normal or a bug?