Shaco's Box's (W) Don't Trigger Item Passive Tribute

Shaco's boxes don't trigger Tribute from Spellthiefs blade and other similar items.

His boxes are pets and all other pets trigger the passive of spell thiefs blade.

Zyra's Plants Shaco's Clone Malz's voidlings

All the above trigger Tribute but for some reason Shaco's boxes do not.

Other abilities like Morgana's Pool will even trigger tribute multiple times.