I know, I set the status to last from a minimum of 2 turns to a maximum of 3, but for some bug it becomes infinite!
And I can't understand why!
I took a look at it. Stunned (and Sleep) has Auto-Removal Timing set to Action End, which never happens because the state keeps the target from acting. It needs to be set to Turn End instead. You'll also want to have YEP_CoreEngine load before YEP_BattleEngineCore, or else it'll last half as long as it should.