Alert tuning for Custom detection rules

We’re trying to set up an alert tuning rule for some of our custom detection alerts. The rule itself is straightforward: it should automatically resolve alerts based on the alert name and a few additional conditions. However, it doesn’t seem to work.

I came across this thread: Alert Tuning (formerly Alert Suppression) Issues | Microsoft Community Hub.

Unfortunately, the article linked there doesn’t mention anything about custom detections.

Does anyone know whether alert tuning still doesn’t support custom detection alerts?

What seems to be the issue with the alert tuning?