In your case, my advice, is for you to use AIPerception component, instead of PawnSensing.
Create a sight sense and then it’s just a question of:
If you still want to use PawnSensing then check this one [https://answers.unrealengine.com/questions/129060/pawn-sensing-false.html][2] or [https://forums.unrealengine.com/development-discussion/blueprint-visual-scripting/30202-help-how-to-detect-when-pawn-sensing-is-not-active][3].