I am following up on this post for the community. The answer below comes from the support request that was submitted in parallel with this post. The issue was tied to a trial account playback issue.
The fundamental difference between trial and paid Cloud accounts are that the playback URLs for paid accounts are served from the CDN. For trial accounts the streams are served from the same server that ingested the source, essentially the same way that Wowza Streaming Engine would function (if you’re familiar with that product).
So it is possible that on some browser/OS combinations the trial stream is causing an issue. I’ve not been able to reproduce this myself though.
The other reasons for CORS errors are when the Live Stream has not started, or nothing is being published to it, but I’m guessing when you were testing it was active.
Having a full Wowza Streaming Cloud subscription is obviously the way to go though if you’re looking at providing streams to more than a handful of people.
I hope this helps.