Supabase Realtime Broadcast Not Working from C# Backend

Hey everyone! I'm building a chat app with React Native (frontend) and C# ASP.NET (backend) using Supabase Realtime. Messages save to the database fine, but broadcasts from the backend never reach the frontend. // This call hangs forever - never completes
await channel.Send(
Supabase.Realtime.Constants.ChannelEventName.Broadcast,
"event",
payloadRawData
);