JPG Are you talking about custom icons or any glyph icon? I’ve had no problem with the included icons (phone icon or message bubble icon) staying up on the glyph matrix until I pick up my phone to acknowledge the notification. I haven’t tested to see how long it truly takes but definitely more than 2-3 minutes in my testing. I’ll have to see if my custom icon stays on.
Edit: Just tested with my new custom icon and it is staying lit for me until I acknowledge it.