On Android Oreo there was a special location in settings that you had to go to in order to allow an app the turned on the LED to actually be able to control it. Now with Android Pie that setting is either gone or I am not correctly remembering where it was, because I can't find it.
How do I enable an app to use the LED in Pie?
There is a settings option called "Custom Restrictions". I had to search the settings (from the search bar) to find this, but it didn't indicate where it was in the menu structure. Under "While the screen is off" de-select the option that says to not blink. If you do not see this option (as I did not) then you do not have a notification LED on your phone (shocker, I know!) and that is the reason you can't get the LED notification working.
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