Not getting any streamed market data

Using Java with Spring, I don’t have any trouble getting trade updates. I also don’t have any trouble connecting to the market data socket, authenticating and subscribing to streams.

If I send {"action": "listen", "data": {"streams": ["alpacadatav1/BA"]}},
I get {"stream":"listening","data":{"streams":["BA"]}}, but nothing further. No errors are reported. Trade updates stream just fine.

I get the same result without the alpacadatav1 prefix. I also tried it when I wasn’t connected to the trade stream. I was sure it must have been because the markets aren’t open at night, but it’s the same now that it’s Tuesday afternoon.

Any ideas? Thanks.