Is there a list of them?
Not sure how it’s exactly called, though. I mean this: https://imgur.com/a/S2ArXDT
The reason I am asking is because I was pushing in NS this afternoon, and I saw one of these “notifications” I had not noticed before - not sure it was in the middle of the screeen though, perhaps it was more on the right, and I though it might be some effect from an Elite I was fighting. I would probably recognize it if I see it…
The best source I can think of for the information you ask is maxroll.gg/D3.
Edit: Just saw the edit to your post and I don’t think there is a list. They are just random help notifications, almost as a guide for new players. I still stand by my original answer unless someone else can offer a better advise.
Sounds like you are asking about the icons that appear on the buff bar (left side) or the debuff bar (right side) in game. I don’t think there is a list. If it was on the right, it may well have been a debuff from an elite as you suspected.
Some of these icons appear very briefly and go away before you can mouse over to read the description if you are actively fighting.
Exactly. I have updated the post title accordingly.