I stream a church service every week, which doesn't have that problem. We don't have OBS logged into our account. We use the generic URL and stream key.If I don't manually create the new Broadcast before 8 AM, the start macro fails because OBS says a broadcast needs to be created before it can start streaming.
And we don't schedule a stream on YouTube either. There's a persistent one in addition to the scheduled one. I eventually deleted the scheduled one.
Use the stream key from the persistent one, and just start throwing data at it. Again, OBS is *not* logged in; it only knows that key. When the data stops, YT times out and resets, ready for the next one, and the DVR processing starts running on whatever that stream was.
The metadata of the DVR'ed video - title, description, etc. - is whatever the stream had when it timed out and reset. That still needs to be set manually, by logging a normal web browser into the account.
Then the Start Streaming and Stop Streaming actions in Adv. SS "just work".