Active Defense autofire disabling

[Call Me Awesome]

I've noticed on my Elec/Shield Stalker that Active Defense is frequently ceasing to autofire; when I enter a mission the gold Auto ring is getting detoggled and I frequently don't notice it until I get hit by a mez or KB.  I haven't noticed any particular event that causes it; sometimes it's happened when running a Flashback arc, sometimes when running a TF and sometimes just running standard missions.

 

I always have it set to Autofire... sometimes however the gold ring vanishes.  I'm currently level 50 and haven't noticed this in the lower levels; last night it kicked out twice, once on an ITF and once on a Maria Jenkins mission.  I first noticed this a few days ago and it seems to be random, I just suddenly get hit by an effect and then I notice that AD isn't active.