I know there are several similar posts to the one I am creating, but I think it is important to bring this issue up until it gets fixed.
It's very hard to make Edge Lighting work. First, I find the menu quite counter-intuitive, although this is the lesser of the problems. Once I had managed to have Edge Lighting working at all times and I had chosen which apps should trigger it and which colours, I thought everything would be ok. It is not ok. With some third-party apps (e.g., Telegram) it seems to work most of the times; with other apps, such as Signal, the light notification only works when I am using the phone and not when the screen is off. Basically it works in the moments I care the least that it works.
The Samsung S20+ is an expensive phone. Having to waste time on the internet looking for the solution for a problem I should't have is definitely not what I would expect from a flagship phone.