I was having problems with my M5 not connecting to my Google Home and not being able to make it part of a speaker group. It kept dropping out of Google home, but worked with Spotify Direct. I posted the question on the forum in a different section.
I am providing an update.
I did a call with Google chromecast tech support who did an assessment, identified the chromecast version on my M5 was an old version. They send me the logs and I sent it to B&O support team. They acknowledged the issue and said they are working on it. As of yesterday my M5 dropped out of my network. I reset it by unplugging and re-plugging it. I assumed there might have been a software update (I have set my M5 for auto software update).
All issues are now resolved. M5 is connecting to Google Home and I can add it to my speaker groups. All working well.
I have to comment both Google Chromecast tech support and B&O customer support. They were both extremely helpful resolving this issue, and grateful for sending them detailed logs from my systems to resolve this issue