Hello.
From what I see is that YouTube just stops the stream on it's self.
I would suggest trying to do a test stream with just a simple screen and see how long it is before it stops.
The reason the Stop Streaming button is still active is because OBS tries to connect to YouTube again until you stop it as shown here.
Code:
10:44:15.540: [rtmp stream: 'simple_stream'] Connecting to RTMP URL rtmp://a.rtmp.youtube.com/live2...
10:44:45.553: Could not resolve a.rtmp.youtube.com: Unknown error (0)
10:44:45.554: Output 'simple_stream': Reconnecting in 10 seconds..
Once you get the results from YouTube, get back to me and I'll try to help.