Connecting to SignalR from React Native Expo app

I'm trying to connect to my SignalR hub from a new React Native Expo app and I keep getting an error, though the nature of the error is unclear because there's no data provided with the error.

As I said, this is a brand new Expo app so the code is very simple:

import { StatusBar } from 'expo-status-bar';
import React from 'react';
import { StyleSheet, Text, View } from 'react-native';
import { HubConnectionBuilder, LogLevel } from '@microsoft/signalr';

const connection = new HubConnectionBuilder()
  .withUrl('https://my-app.com/test-chat')
  .configureLogging(LogLevel.Information)
  .build();

async function start() {
  debugger;
  try {
    await connection.start();
    debugger;
    console.log('SignalR Connected.');
  } catch (err) {
    debugger;
    console.log(err);
    setTimeout(start, 5000);
  }
}

connection.onclose(async () => {
  await start();
});

// Start the connection.
start();

export default function App() {
  return (
    <View style={styles.container}>
      <Text>Hello World!</Text>
      <StatusBar style="auto" />
    </View>
  );
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    backgroundColor: '#fff',
    alignItems: 'center',
    justifyContent: 'center',
  },
});

Here's what I see in my console:

The npm package I use for SignalR in the app is "@microsoft/signalr": "^5.0.9".

And here's the code in my test-chat hub:

public class TestChat : Hub
{
    public override async Task OnConnectedAsync()
    {
        var connectionId = Context.ConnectionId;

        await Groups.AddToGroupAsync(connectionId, "test-chat");
        await base.OnConnectedAsync();
    }

    public override async Task OnDisconnectedAsync(Exception exception)
    {
        var connectionId = Context.ConnectionId;

        await Groups.RemoveFromGroupAsync(connectionId, "test-chat");
        await base.OnDisconnectedAsync(exception);
    }

    public async Task Send(string message)
    {
        await Clients.Groups("test-chat").SendAsync("new_message", message);
    }
}

I tried connecting in debug mode locally. I also tried connecting to it on an actual app on the web. Either way, the connection is failing. I thought it could be a CORS issue but I don't think we specify anything in the CORS settings for mobile apps.

Any idea what could be the issue here? Has anyone been able to connect to a SignalR hub using React Native (Expo or not)?

UPDATE: One important point I forgot to mention originally is that I'm using Azure SignalR. My Expo client app is still configured to hit the hub that's on my ASP.NET Core backend.

UPDATE 2: First, there was a CORS issue because I was testing this using the Android simulator on my Windows 10 machine and I needed to add http://localhost:19000 to allowed origins. But the second issue is more concerning to me: I do use the Azure SignalR service to make things more reliable and scalable but that's creating an issue. When I switched to just handling all client connections in my ASP.NET Core 5 backend, it started to work.