I'm also having problems with Detox not cleansing my raidmembers when I don't have them targeted.
The problem I'm seeing is that it refuses to dispel people if I don't target them. If I get a debuff myself it will dispel once, and that is me. Sometimes when I target the MT and dispel him from whatever debuff he has, I sometimes can dispel the rest of the raid. And other times it will only dispel the MT and refuse to dispel the others.
I'll try to put on the debugging part next time but I'm no wizard in this topic so.. :)
PS! Dispelling on myself is fine, just not on the raidmembers without needing to single target everyone.