I have my google nest wifi point in a 'downstairs' group with two paired nest audios and a 2nd gen mini. Due to all sorts of weird issues, I turned off the microphones on all but the wifi point, which means I have to raise my voice a bit to be heard from farther away, but at least it usually works without the weirdness when multiple microphones are turned on. The 'default speaker' set for the wifi point is the 'downstairs' group, which works for music. However, when I ask Google assistant to play a podcast, it will only play on the wifi point, while I want it to play on all devices in the group like the music does. What gives? I believe that it used to play all audio on the default speaker (the 'downstairs' group), not just 'music'. Rebooting hasn't helped.
Sorry for the late response here, but I wanted to check in to see if you were still having this issue and to see if you have done any troubleshooting so far. If you still need help, let me know and I'll be happy to work on this with you.
Just one quick final check in here since activity has slowed down. We'll be locking the thread in the next 24 hours, but if you still need help, I would be happy to keep it open. If there's more we can do, just let me know.