Luminark was always a very niche pick, barely usable and only when you get a perfect map and surprise your opponent, which usually works only because no one really expects luminark.
That was pretty much fine, because it is basically THE sniper of the game. With too much buffs, it could become abusive on some instances.
After the latest patch, however, Luminark is absolutely useless. Literally anything can stop priming of the shot (opponent leaving area, a slight turn or a bump or just a single arrow hitting luminark can make order get dropped... are just some examples). When that happens, the shot is completely cancelled and it needs to prime again, which takes a lot of time.
Honestly, the old way of having Luminark fire its shot after a certain point even if it moves was better than this. Luminark went from "very niche" to "absolutely useless".
Order drop bug is not just a problem of the luminark, of course, and it certainly needs to be addressed, as soon as possible. That alone won't fix the luminark issues, it probably needs to turn and shadow its targets movement while targetting/priming, otherwise pretty much anything will leave it's targetting radius, and cancel the shot. Or simply have a luminark fire it's shot after priming reach a certain point regardless of what happens, like it used to.