To everyone experiencing issues with Chromecast audio lagging in Oculus Home & being disabled for every single game, I've posted the issue onto the bug tracker: https://developer.oculus.com/bugs/515262895515014/
Please post your experience with Chromecast there so Oculus will see it. If we're lucky, they may even communicate a meaningful update regarding the progress of this investigation.
S7 Exynos Nougat. 2017 Gear VR. Public test channel.