ReplicatedUsing doesn't work in Replicated Subobject UE 5.1

[Tioxii]

So, recently I have been trying to implement an InventorySystem in UE using C++ and Blueprints. For this, I implemented an ItemInventoryComponent with a TArray containing InventoryItem objects. I use the corresponding replication system as shown in the code down below. My problem now is that in the InventoryItem object, the ReplicatedUsing function, On_RepQuantity(), is not getting called when the Quantity changes, and I don’t know why. For more context, the OnRep_Items() functions in the ItemInventoryComponent works as it is supposed to. Also, the value is being replicated to the client, but the On_RepQuantity() is just not being called. I don’t know if I did something wrong or if this is default behavior or a bug I have encountered.

InventoryItem.h

virtual void GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const override;

virtual bool IsSupportedForNetworking() const override;

UFUNCTION(BlueprintNativeEvent, Category = "Inventory")
void OnRep_Quantity();

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory", Replicated, meta = (ExposeOnSpawn = true))
FName ItemID;

UPROPERTY(EditAnywhere, BlueprintReadOnly, Category = "Inventory", ReplicatedUsing=OnRep_Quantity, meta = (ExposeOnSpawn = true))
int32 Quantity = 1;

UPROPERTY(BlueprintAssignable, Category = "Inventory")
FRefreshQuantity RefreshQuantity;

InventoryItem.cpp

void UInventoryItem::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
{
    Super::GetLifetimeReplicatedProps(OutLifetimeProps);

    DOREPLIFETIME_CONDITION(UInventoryItem, ItemID, COND_OwnerOnly);
    DOREPLIFETIME_CONDITION(UInventoryItem, Quantity, COND_OwnerOnly);
}

bool UInventoryItem::IsSupportedForNetworking() const
{
    return true;
}

void UInventoryItem::OnRep_Quantity_Implementation()
{   
    if (RefreshQuantity.IsBound()) 
    {
        RefreshQuantity.Broadcast();
    }
}

ItemInventoryComponent.h

virtual void GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const override;

UFUNCTION(BlueprintNativeEvent, Category = "Inventory")
void OnRep_Items();

UPROPERTY(EditAnywhere, BlueprintReadWrite, Category = "Inventory", ReplicatedUsing=OnRep_Items)
TArray<class UInventoryItem*> InventoryItems;

ItemInventoryComponent.cpp

UItemInventoryComponent::UItemInventoryComponent()
{
	PrimaryComponentTick.bCanEverTick = false;
	bReplicateUsingRegisteredSubObjectList = true;
}

void UItemInventoryComponent::BeginPlay()
{
	Super::BeginPlay();

	for(UInventoryItem* item : InventoryItems)
	{
		AddReplicatedSubObject(item);
		CurrentInventorySize++;
	}
}

void UItemInventoryComponent::GetLifetimeReplicatedProps(TArray<FLifetimeProperty>& OutLifetimeProps) const
{
	Super::GetLifetimeReplicatedProps(OutLifetimeProps);
	DOREPLIFETIME_CONDITION(UItemInventoryComponent, InventoryItems, COND_OwnerOnly);
}

//Notify Inventory has changed
void UItemInventoryComponent::OnRep_Items_Implementation()
{	
	if (RefreshInventory.IsBound()) {
		RefreshInventory.Broadcast();
	} 
}

[Tioxii]

Resolved the issue by replacing this:

DOREPLIFETIME_CONDITION(UInventoryItem, Quantity, COND_OwnerOnly);

By this:

DOREPLIFETIME_CONDITION_NOTIFY(UInventoryItem, Quantity, COND_OwnerOnly, REPNOTIFY_Always);