Pinch zoom for touch screen

How do I use Pinch (as in tablet touch screen pinch)? Under project settings, I set Axis Mapping → ZoomPinch to Pinch with Scale 1.0. Then I did C++ code:

InputComponent->BindAxis("ZoomInPinch", this, &AHQSpectatorPawn::ZoomPinch);

Plus:

void AHQSpectatorPawn::ZoomPinch(float AxisValue)
{
	GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("ZoomPinch %f"), AxisValue));
}

But when I print via AddOnScreenDebugMessage(), I always get 0.0f for AxisValue?

Update: Can someone confirm that UE4’s Input → Axis Mapping → Pinch, works at all? I tried it with my kindle fire but it just spits out 0.0f’s constantly regardless of whether or not I touch the screen.

None of these gestures work with UE 4.13 either - Pinch, Flick, Rotate. I don’t understand why they are even there since they do not work