Have you tried on other weapons? Because I'm using puppet rune on my shadow axes and it works even if used with trap rune. Although I noticed that I can only see the puppets' movements only during slow motions (after defeating a boss or a player, and finishing dungeons) but that could be just my device' slow refresh rate.
Don’t work with me and I’m using shadow axes only works with traps ..
Activates on crit but works normally with trap rune. I saw Shimmer Studio commented on it in their FB page