I don't seem to have a problem with the chests themselves, I can get the treasures just fine. Are you being seen when you're picking the lock? Or are you looting the chest after picking it? (assuming you don't auto loot). I won't get an update if I happen to be seen, so timing is important. Though I don't know if that is your issue. I don't do the heists myself because invariable, I always get seen/ trapped by the wandering named on my way out and lose too much time. I loathe the heists. I'm rather good at and fond of the DB Sacraments though and I know those frustrate some people too, so maybe it's just a matter of play style.

As far as trading goes, just use zone chat unfortunately, or a forum post? In chat though, you can also link your style master achievement list do people can see what motif you need without you typing everything out.