In your 0.554 log file, make note of this:
Total frames rendered: 1228, number of late frames: 780 (63.52%) (it's okay for some frames to be late)
and this:
frame - [100%] [avg time: 23.748 ms]
You are not actually encoding at 60fps even in 0.554. You are encoding at approximately 41ish FPS average total. Due to the fact that encoding is taking so long, even in 0.554 you are not getting 60fps. Which means that 0.554 was not actually performing perfectly for you either. The majority of your frame timings were late.
In 0.57, it now forces the stream to send at exactly the FPS you set to prevent encoder issues and to prevent twitch streaming issues, so it was not giving you that warning in error, it was a legitimate error given because you are set to a framerate you cannot actually handle. I would recommend setting your stuff up to 30fps. Maybe 40 at most (because you already can't get much over that anyway regardless of version)