Q600A at least the UK variant never has had Smartthings connectivity, it does have tap to play which needs to be switched on within Smartthings but that does not mean the Soundbar is connectable to ST as a device
The sounbar does show up in personal devices but that is only due to BT connectivity for audio
I agree it would be nice to have but it is sold at a price point, a more expensive version would have ST connectivity
On a side note, the bass is excellent, center is excellent but steering can be a bit lacking I have found but it is what it is, overall I’m very happy with it and looking to get the rears with the wireless connector but using my own already installed but unused orbs for rear speakers