Android Notification when phone is closed/screen turned of

We're having the problem that the notifications always gets delivered for both iOS and Android but on Android there is no sound/display/vibration when the notification is received. Oddly enough it is working on a very old Android phone we are testing with but with newer phones the notification just gets "silently" delivered i.e. shows up in the Android navbar but the user doesn't see/hear it unless opening the screen.

Could somebody somebody who has Android notifications working (with sound/vibration/screen popup) share payload/snippet of what is being sent to make this work? We're using .NET Framework 4.8