Your HLS content is not casting to Chromecast via JW Player, is this a CORS config that you need to setup?
I am able to view in my JW Player embed the stream on desktop and ipad but it will not cast to chromecast.
I am well versed in the config of Chromecast with JW Player and HLS, I have been able to cast HLS VOD content
So I believe the problem is that you either need to allow extra CORS or the other possibility is that the stream URL is http and not https and my webpage is https. The URL provided to the M3U8 is http and does not seem to work over https