GAMEPLAY BUG THRESH ACTIVATING SUPPORT ITEM

Hey guys :)

Not sure how big of a bug this might be since i don't play thresh often but the few times i have i've always had this issue with proc-ing the support item "Relic Shield" Leona/Braum/Alistar are able to proc it with the minions at 60-70% health yet many times i've tried with thresh at 30-50% health(minions) and it still won't proc. I see it as a huge disadvantage which leads me to rarely play as thresh. Please i'd like to get feedback on the subject if it's just me experiencing this or if it is meant to be this way. <--- also it's easier to note the difference in early levels of the game.