We have the same issues but with VOD and using Cloudflare Steam and VideoJS. The quality would stay very low even though we're on a 500 Mbps Fiber connection. We've moved over to the BitMovin Player now and almost immediately received the 1080p version. I think it's in the way CF builds the manifest, or something with the first segments. We couldn't solve it either. But as we were already using BitMovin in our App, we've migrated our Web App too which solves it. However we also are still receiving complaints from users using Chromecast that the quality isn’t up to par.