I think I've narrowed down the /castrandom issue I've been having. It happens in this macro:

/castrandom Holy Shield, Shield of Righteousness, Hammer of the Righteous, Divine Plea, Judgement of Light

If I make a bar with all those abilities and watch it, during every fight one ability is picked and will never be triggered. There is a good few seconds of dead space where I'm hammering the button and all the other spells are on cooldown, but that one ability won't trigger, the whole fight. The next fight it'll do the same with another ability. Sometimes it'll leave out Shield of Righteousness, sometimes it won't cast the Judgement, sometimes (The most dangerous times) it refuses to cast Holy Shield.

This is consistent, not a result of the random number generator as far as I can tell. We're talking a 0% chance for that specific spell to cast, it never fails. However, I did notice that if I take the Judgement of Light out, it works PERFECTLY. Does anyone know something special about Judgement of Light that ruins /castrandom sequences?