if the phone can hear you and confirm to you that it accepted your voice setup, yet you can't use it in normal day to day situations, then there is something else that's blocking the use of bixby, and to find this out over the internet is going down a major rabbit hole.
I mean you could have background processes turned off, something disabled, etc... using bixby is not rocket science. if you speak into it loud enough, it will activate, even if you did NOT set up your voice to work with it.
perhaps you can clear cache and if that doesn't work, factory reset...
