OK, I'll just say that the complaints are totally legitimate. But the author seems to be missing something that I only recently discovered myself. You can tell

OK, I'll just say that the complaints are totally legitimate. But the author seems to be missing something that I only recently discovered myself. You can tell Music on macOS to sync to the cloud immediately by selecting File > Library > Update Cloud Library. It presents a spinner at the bottom of the window showing progress. (Well, showing that it's still working.) After that, if it doesn't immediately show up on your phone, you can force-quit the app and restart it and it should be there. I write a lot of music and like to be able to play it on different devices (phone, HomePods, in the car, etc.). It took me a while to figure the above out!