Try it with a const and reference for the TArray (it should be immutable)
.h
virtual void FindTarget_Implementation(const TArray<AActor*>& ActorsInRange);
.cpp
void APlayerC::FindTarget_Implementation(const TArray<AActor*>& ActorsInRange){
}
and delete the non _Implementation version (the base) from the cpp or it will throw an error on compile.
to clarify get rid of
void APlayerC::FindTarget(TArray<AActor*> ActorsInRange){
// your code here
}
from your cpp if it’s there.