Over the past week I've been struggling with matchmaking issues, with the matchmaking polling always returning as cancelled with a reason of 'Internal' (this is through unity) and initially believed the reason to be related to Server API calls I was attempting to make.
But after testing locally and with the multiplayer agent, I am strongly suspecting that there is an issue with my title id and the matchmaking engine.
To test this theory further, I created a new server build from an existing validated (and working) branch, uploaded it to the multiplayer servers, and changed the matchmaking queues I was testing to point to that new build. Any matchmaking tickets that were attempted were cancelled by the server for that one too.
The only successful time I was able to get matchmaking working again was by switching the queue to point to a build I had uploaded months ago (that was the same as the existing branch I uploaded today). It seems like something has happened between then and now but with Unity only returning 'Internal' as a reason for cancellation I'm stuck.