Just hiding really well? I put a peppermint in my last tank and he was mia for months, then one day he decided he’d post up right in the front like he had been there the entire time
the only fish I’d maybe suspect would be the bangaii. cirrhilabrus and paracheilinus are planktivores and i doubt would even be able to consume even a small peppermint. they don't have mouths with the crushing strength to take out an invertebrate like a halichoeres or something would, plus they don't eat stuff off the rockwork, that just isn't their game
cardinals on the other hand don't mind eating fairly large stuff with their big ass mouf