Volume always 'None' in streamer

[starsnpixel]

This is a question not so much related to the development (thank you so much once again!) but to the users:
Is your streamer delivering proper values for the TTV volume? Mine always returns 'None', everything else works fine. Fetching by REST does yield volumes. I just use the regular setup:

ig_service = IGService(
        config.username,
        config.password,
        config.api_key,
        config.acc_type,
        acc_number=config.acc_number,
    )

ig_stream_service = IGStreamService(ig_service)
ig_stream_service.create_session(version='3')

market_subscription = Subscription(
        mode="MERGE",
        # fx_epics, index_epics, weekend_epics, futures_epics, cfd_fx_epics
        items=[f"CHART:{epic}:1MINUTE" for epic in markets['ID']],
        fields = ["TTV" , "UTM", "OFR_OPEN", "OFR_HIGH", "OFR_LOW", "OFR_CLOSE",
                     "BID_OPEN", "BID_HIGH", "BID_LOW", "BID_CLOSE", "CONS_END"],
    )

# adding a listener to MARKET subscription
market_subscription.addListener(MarketListener())

# registering the MARKET subscription
ig_stream_service.subscribe(market_subscription)

def onItemUpdate(self, update: ItemUpdate):
        if int(update.getValue('CONS_END')) == 1: 
           print(update)

So the question is: Is this a bug or a feature by IG? I can also not rule out a misconception on my side, of course. 😆