question

I have a short question.

I am trying to add an item to a player and then put a custom class on it:

// update the data on the new item
var updateItemRequest = new UpdateUserInventoryItemDataRequest()
{
	PlayFabId = context.CallerEntityProfile.Lineage.MasterPlayerAccountId,              // Way to get PlayfabID
	ItemInstanceId = _itemGranted.ToString(),      // Id of this specific item
	Data = new System.Collections.Generic.Dictionary<string, string> 
        {
        {"BuildingData", JsonConvert.SerializeObject(_buildingData)}
    	}
}; 

var updateItemResult = await serverApi.UpdateUserInventoryItemCustomDataAsync(updateItemRequest);

I am getting the right ItemInstanceId and otherwise I am not quite sure what is wrong.

Thank you for your help.

Edit: this is the class I am trying to convert into json: