The management of the default speaker / Bluetooth speakers is completely broken.
I am pairing a Fossi amp (BT 5.0) with my hub. I can BT pair and set the amp as the default speaker, but all sound (not just media) continues to play through the Nest/Hub even when the Home app shows the amp as the selected default and the hub itself says the amp has been selected as default, and the amp confirms it has a BT connection. After attempting to connect for hours, I somehow got music to play through the amp, but bizarrely the Home app says the Hub display is the currently selected default speaker, not the amp. The accompanying screen shots were taken while music was playing via the amp, NOT the Hub display.
For some reason it shows 2 Fossi connections on the default selection page, while showing only ONE on the paired device page.
I have had ZERO issues pairing with and streaming to the Fossi amp with my Pixel via BT, so the problem is not the Fossi.
I tried rebooting, unplugging, and finally a factory reset. Nothing has changed.
