Not receiving alerts to watched threads

Apparently there is some maximum amount of notifications that is sent to someone that is watching a thread.
I no longer receive notifications for the following thread:
https://forum.unity3d.com/threads/unity-patch-releases.246198/page-4
even though I am set to watch the thread.

This happens for all threads which I have been watching for an extended period of time.
I tried Unwatching the thread and re-watching it, but I still don't receive the alerts.
I no longer receive the alerts from asset store item threads either.
The problem seemed to start after Unity rolled back the old forum.

I said I think there is a maximum amount of notifications sent, because I've created my own threads only to stop receiving alerts to responses after about 10 notifications were sent to me.

What if an asset store seller creates a thread for support, only to not receive an alert if someone posts a question or asks for support using the forums?