Realtime API room subscription: seeing only my own messages



I’m connected to the realtime API. I am using this call to subscript to a room:
“msg”: “sub”,
“name”: “stream-room-messages”,
“id”: “1609de47-ec8f-4f7b-95b2-b48464ee49b7”,
“params”: [

This is acknowledged with a sub reply:
“msg”: “ready”,
“subs”: [“1609de47-ec8f-4f7b-95b2-b48464ee49b7”]

When I use the Rocket.Chat webpage or the REST or the realtime API to post a message to the room, I receive my own message back: { “msg”: “changed”, “collection”: “stream-room-messages”, … }.

However I receive ONLY my own messages. Posts by other users are not received. What am I doing wrong?

Cheers, Torsten