BUG? USubsystem inheriting from FTickableGameObject keeps ticking while paused

I need to use tick on my subsystem, but there seems to be a bug, can anyone confirm if this is true?
I expect the Tick function not to execute while the game is paused but it does. when printing the return value of UGameplayStatics::IsGamePaused(this) within Tick, It keeps switching between true and false, which is odd already, but I did not expect the Tick function to execute at all when the game is paused. What is going on here in the engine? I confirmed that the game is paused and unpaused correctly.

Test Subsystem .h :

#pragma once

#include "Tickable.h"

#include "TestSubsystem.generated.h"


UCLASS()
class UTestSubsystem : public UGameInstanceSubsystem, public FTickableGameObject
{
    GENERATED_BODY()

public:
	// Begin USubsystem
	virtual void Initialize(FSubsystemCollectionBase& Collection) override;
	virtual void Deinitialize() override;
	// End USubsystem
	
	// Begin FTickableGameObject
	virtual bool IsTickableWhenPaused() const override;
	virtual TStatId GetStatId() const override;
	virtual void Tick(float DeltaSeconds) override;
	// End FTickableGameObject
};

Test Subsystem .cpp :

#pragma once

#include "TestSubsystem.h"


// Begin USubsystem
void UTestSubsystem::Initialize(FSubsystemCollectionBase &Collection) {
	Super::Initialize(Collection);
}
void UTestSubsystem::Deinitialize() {
	Super::Deinitialize();
}
// End USubsystem


bool UTestSubsystem::IsTickableWhenPaused() const {
	return false;
}

TStatId UTestSubsystem::GetStatId() const {
	return UObject::GetStatID();
}


void UTestSubsystem::Tick(float DeltaSeconds) {
	if (UGameplayStatics::IsGamePaused(this)) {
		if (GEngine) { GEngine->AddOnScreenDebugMessage(-1, 4.0, FColor::Red, "TimeSubsystem: PAUSED"); }
	}
	else {
		if (GEngine) { GEngine->AddOnScreenDebugMessage(-1, 4.0, FColor::Green, "TimeSubsystem: NOT PAUSED"); }
	}
}

Every tick this seems to be Valid and then Invalid, then valid again… Makes no sense?

UWorld* WorldTest = this->GetWorld();