Family check
AutoPPC will never negate a term if any variant of it has orders anywhere in your account.
"Cast iron skillet," "cast iron skillets," and "cast-iron skillet" are one term to a shopper and three rows in a report. Judging any one of them alone will eventually kill a phrase that is quietly carrying the family.
Before any negative, AutoPPC assembles the whole conversion family and checks it. If any variant has orders, the negative is blocked — not flagged for you to override, blocked.
This is an Invariant. It is also the single most common way an account gets damaged by automation, and most tools warn you about it rather than preventing it.