fyNone of the below information is required. However, the more you provide the easier it will be for us to try and help.

Plan

Premium

Country

 Australia

Device

iPhone x

My Question or Issue

 I have 5 Chromecast devices and two groups. When I put any of the devices in a group, the group appears and works fine but the individual chromecast device becomes missing from the list. I have an additional 4 Chromecast Ultra's for the TV which still appear on the list. 

I can play to the missing chromecasts through the Google Home but when I try and control the stream with my app it crashes. Otherwise I have to ungroup the chromecasts from the Google Home app each time I want to pick an individual cast.