placeholders in metaskills of shoot mechanic

mmocore placeholders not working in metaskills of shoot mechanic Console Error but in shoot mechanic itself the placeholders work fine (in their string)

MythicMobs 5.0.0 b314745b MMOCore 1.9-SNAPSHOT 205

in this example <modifier.damage> and <modifier.arrow_distance> work good (becouse they in shoot mechanic string itself) but <modifier.stun_duration> not working becouse it is in metaskils of shoot mechanic

Archer_NoSpec_PinningShot:
  Conditions:
  - holding{m=BOW} orElseCast Archer_NoSpec_Weapon-Error
  - moving castinstead Archer_NoSpec_Moving-Error
  Skills:
  - sound{s=entity.arrow.shoot;v=1.5;p=0.25}
  - shoot{
      type=ARROW;velocity=1.05;
      damage="<modifier.damage>";
      md="<modifier.arrow_distance>";
      onTick=[
        - effect:particlesphere{
            p=block_crack;m=dead_bush;amount=25;radius=0.5;y=0.25} @origin
        - sound{s=entity.ender_dragon.shoot;v=0.03;p=1.0} @origin
      ];
      onHit=[
        - sound{s=entity.arrow.hit;v=1.0;p=0.25}
        - aura{auraName=Сковывающий выстрел;
          onTick=[
            - effect:particlesphere{
                p=block_crack;m=dead_bush;amount=25;radius=0.5;y=0.25} @origin
          - sound{s=entity.ender_dragon.shoot;v=0.03;p=1.0} @origin
          ];
          interval=2;duration=200}
        - potion{
            type=SLOW;
            duration="<modifier.stun_duration> * 20";
            level=7;i=false;p=false}
      ];
      knockback=0;pickup=false} @Forward