I don’t understand this forum. My replies don’t show up or they disappear. So if you end up reading everything three times, just take it easy 
First of all, thank you so much for your help!
Screen1 shows a black screen after starting the stream. After about a minute, Screen2 appears: the start screen of the stream with a constantly spinning circle in the middle.
Brave Browser is up to date (and freshly installed). Version 1.71.114 Chromium: 130.0.6723.58 (Official Build) (64-bit).
I’m using Windows 10 Pro on a desktop PC, Version 22H2, OS Build 19045.5011, Windows Feature Experience Pack 1000.19060.1000.0.
I’ve tried completely disabling Shields as a test, but no change — the stream still doesn’t work.
I’m not using any extensions, except the pre-installed “SponsorBlock for YouTube.”
I tried starting the stream in a private window — both with and without TOR: no success.
I added a new profile, and what can I say? The live stream works! That’s wonderful! 
I have to admit I haven’t been using Brave Browser for long. I modified it as recommended in many YouTube videos. It’s possible I enabled a setting that’s blocking streaming videos. But how do I figure that out? Obviously, the attempts mentioned above (like turning off Shields) weren’t successful.
What setting might I have accidentally enabled or disabled? Of course, I could compare the settings between the old and new profiles, but forgive my laziness—that’s really tedious with the endless number of options. In the end, I’ll probably have to do it, I’m afraid. Unless you have the ultimate solution for me 
Thank you very much!