The black screen issue went away after I uninstalled the Oculus desktop app that I was using for Oculus Link. I noticed it kept opening when I built to the headset. It also started around the time I got Oculus Link working. I can't think of any other factors at play. Please confirm if this fixed it for you as well!
Also been starting to see this problem (with 2019.4.4f1 and the latest Oculus Integration Asset). I first saw the issue about a week ago but at the time there was also a new version of the Oculus Integration Asset that had just been published and when I upgraded the issue seemed to fix itself. Maybe it was somehow a bit of a coincidence that it apparently fixed itself last week - maybe it wasn't related to the new version of the asset. Now I'm already on the latest version of the asset I'm not sure what to try and this is stopping me from being able to share test builds of my application on the Quest 😞
I still have this issue. Oculus SDK 18 (tried 17 and didnt work). Unity 2019.4.6f (latest LTS). Everything compile and even run under Link/PC. But when the apk is generated for android and sent to the quest it displays a black screen.