TF and static shiv interaction.

so basically as i was dicking around in bots for the first win of the day i decided to hit it up with that attackspeed tf. i noticed after i got shiv and used a W card on a tower it would consume the charge and do the effect but not add extra damage.

furthermore this only happened with blue and gold card. red card would still consume the charge and do no damage however if there was a unit nearby when the redcard hit it would apply the effect to every enemy unit near it and damage them.

did i come across a bug and not realize it or this an intended interaction?