Service Bus Message not matching correlation Filter

Question

I have a .NET 6 Azure Function sending messages to a Service Bus topic and I am setting a custom property with this code:

messageToSend.ApplicationProperties.Add("Label/Subject", subject);

... where for the specific Service Bus topic I'm having issues with the value for subject is passed as TASK.

I have a correlation filter setup as show in the image below

What I am finding however is that all messages are ending up in a 'catch-all' topic which has the following default filter setup.

For reasons (yes reasons) our DevOps team have informed us that we need to setup correlation filters to use Custom Properties and not System Properties.

Is there a way in the logs to find out why none of these messages are matching the correlation filter?

Or is there an obvious glaring error I'm making?

Answer 1

This scenario should be working.

Looking at the message, you'll see the custom property/header with the value.

The issue is most likely with the topology setup (subscription and rule).