Does not work for me, either. I'm giving up for now with S10 - send it back to stock...I don't see many progress since s8..more regression I would say regarding this LED notification and trying to workaround it with Edge Lighting which does not work at all
In your settings, Display > Edge Screen > Edge Lighting. Enabling this allows it to work but you'll need to set the edge effect by just tapping on the words instead of the on or off button, there you can change the effect of the lighting and which apps it works for. I hope this helps!
It works only with few applications (e.g. default Text app)...so for which app does not work:
WhatsApp seems to work but it shows edge lighting only once, so it cannot be repeated e.g. every few seconds till user will look on it
here is the thread when another user was testing this real time yesterday..
I think by default edge lighting is turned off when display is off. go to settings -> display -> edge screen -> click on " Edge lighthing" (not the slider) -> Change 'Show Edge lighting' to always