What is the Heroic Strike queue “feature/bug”?
While an “on next attack” ability such as Heroic Strike or Cleave is queued, the miss penalty from dual-wielding is removed. This means your OH swing will have the same miss chances as if you were wearing a single one-handed weapon (6-9% hit cap) until your next MH swing occurs, consuming the Heroic Strike, or you cancel the Heroic Strike queue yourself. The HS queue bug does not remove the chances to glance.
If an OH attack finishes simultaneously as the MH queue’d attack, it does not benefit. This is why same speed weapons on alliance are less favorable; horde has their weapons desync frequently via Windfury and thus are less penalized.