Notifications for auto-reg and internal events are not carried out if the media type for the respective user(s) is set to accept "Not classified". This is not documented, as far as I can see and confusing to.
Since there is no severity for this kind of events, I would expect the notifications go out regardless – just like they do for "Database down". One can argue whether the temporal constraints should be considered or not.
I tried with 2.2.5 and there seem to be no changes in .6 and .7 regarding this.