Baldi and other characters will stay if the player is in the lock

[szymonkruk2000]

Baldi will still get the player if the player is hidden

[Chinese123PaRappa]

That's intentional. The reason they do that is because they either saw you go into the locker or they heard you going in. For it to actually work you need to use WD-No Squee on the locker and then go inside. This won't work if someone saw you go in even after using it.

[|i.c.c.n|]

I have never seen a character stay outside the locker if they've seen you go in unless it was a Principal in the Stealthy challenge since he can't lose you once aggro'd in that challenge... so either I've gotten good luck or there's some misconception I've somehow never heard of before

other characters I've seen wait outside of lockers are those that can hear you, i.e Baldi and an angered Dr. Reflex