Cast when stunned + minion pact

Hi, I tried to make a build that on cast when stunned casts forbidden rite of soul sacrifice which is supported by minion pact. The issue is, it does cast the forbidden rite but doesnt consume the spectre. After thoroughly reading the supports I've come to a conclusion this is a bug ? Cast when stunned does support forbidden rite, and minion pact doesnt state anywhere it cannot be triggered, it also supports forbidden rite. When I cast it manually it does consume a spectre.

Triggered skills are not cast/used.