Email/slack notifications for alerts stopped working

I have tried debugging for several hours, but nothing works, it says firing, but is not picked up, when i test eg slack it works, but hooking it up to the alert stopped working around 5-6 days sto.

I raised a support ticket but to no avail, i can see events firing but no notifications going out.

Any help would be extremely appreciated, as this is getting critical

Bump.