Instant rotation is probably a bug. Try setting bUseControllerDesiredRotation flag in pawn’s blueprint (c++ = in movement component, CharacterMovement property) to enable use of RotationRate and modify AAIController::Tick
void AAIController::Tick(float DeltaTime)
{
Super::Tick(DeltaTime);
UpdateControlRotation(DeltaTime**, false**);
}
It should get rid of forcing pawn’s rotation in every frame and give movement component to interpolate.