I finally see the Default Audio Output option but it still only shows TV Speakers as the selectable option. However the workaround of using the TV (Home) Button on the Apple TV remote still works and I can select the HomePods but defeats the purpose of Default if you manually have to do this every time. It is still unclear to me why they dont appear under the Default Audio Option as I have an AppleTV 4k its running the latest TVos release the HomePods are running the current iOS 14.1 as there is no other update to apply. I am not sure if there is any smarts behind Default Audio Output if it checks your Region for example and assumes since mine is set to Netherlands that it concludes since Homepods are not sold in NL they are not available for selection. I bought my HomePods across the boarder in Germany. The language settings on both HomePods and the AppleTV are both set to English as I am an expat and speak zero Dutch

Funnily enough not long after posting this iOS14 Beta 6 and tvOS 14 Beta 6 was released. I applied both and Automation is now working again and the events trigger on time based automation not sure about sunset or sunrise will need to test those as sunset has already passed and sunrise is 8 hours away

I get the same BIDomain Error 3 when trying to install in VMware Fusion and selecting the existing virtual disk that has Catalina Beta installed

Thanks for the advice your first suggestion no such option appears for Default Audio Output on my apple tv 4k model A1842 (64 GB) using tvOS14 beta However your second option provided a suitable work around by holding down the TV button So thanks