Quinn's W prevents turret executions
If you are out of vision of Quinn, and she uses her "Heightened senses" (W) you won't be executed. It's a status effect. I dunno if a bug or intentional
2 Comments
Well 
little ghosties also give assists provided they spot someone.
It also applies a reveal debuff, so that is a possible reason.
It applies a vision debuff (the ghosty eyes above you) like Kalista's Sentinals do, so it's not a bug