Azure Functions with Azure SignalR returning error 500 after successful Negotiate
I have setup an Azure SignalR service (Serverless) with Azure Functions (Isolated).
I have the Azure Functions service configured with a Microsoft Identity Provider.
I can login with Microsoft correctly and use the token received to call the Http function Negotiate, which works correctly and returns the URL and Access Token needed to connect with the HubConnectionBuilder.
The HubConnection is also successful, but the OnConnected function doesn't get triggered.
Then trying to manually invoke any other SignalRTrigger function returns a 500 error, and I can't see the function ever being executed in the logs, so I can't figure out why this is happening.
My Azure SignalR service has System assigned identity turned on, and I have two upstreams configured - one with the signalr_extension key and one with the default Azure Functions key (in that order) - both with the Use Managed Identity option selected and Select from existing Applications pointing to the Azure Functions Identity Provider App Registration.
I also have the Configuration settings in Azure Functions with the AzureSignalRConnectionString (tried changing it but then the Negotiate function also returns a 500 error).