A customer who was locked out cannot get a password reset email

Their address is locked out for guessing: somebody there typed the wrong password too many times. While Limit password reset emails is on, the lost-password form tells that address the same thing the sign-in form does, Too many sign-in attempts from here, with how long is left. Signing in is refused to that address for exactly that long whatever password is typed, so a new password would not get them in any sooner.

To let them in now, press Let in on their row in Who has tried. That lifts the lockout and starts the reset count again for that address, and they can ask for their email straight away.

If the same account keeps being asked about, it is a real username somebody has found, and it is worth checking that account has a long password and a second step.