I've been researching this for days and cannot find a solution.
Pixel Tablet running the latest version of GrapheneOS with a second "multiuser" account with Google sandbox installed, and the "Home" app installed, signed in, given network permission, devices listed.
When I try to cast from the Musicolet app, it says "no devices found". When I try to cast from clicking the quick tile it says no devices and when I click settings it takes me to "system > connected devices > cast > no devices found". In the home app, when I hold down the tile of the device I want to cast to, the casting option doesn't show(source).
I tried casting from apps like Castify, it works, but only from my browser, not the Musicolet app.
Apparently this has been a problem for 2+ years. Any suggestions?