If the Sonos API’s are at fault (which I do not completely believe since this feature worked perfectly before ST made significant changes and experienced backend platform issues, absent Chat/Help Desk, etc).
If you own a Sonos, you can access it via "The Hidden Sonos Web Interface".
A few other Sonos 3rd party integrators appear to not have this integration issue? For example, I have a Sonospad, a third party iOS APP that works perfectly. Also there is a simplified HTTP API for Sonos to simplify automation. It is hostable on any node.js capable device, like a raspberry pi or similar.
I do understand that Sonos is updating and releasing new API’s to allow more capabilities in direct response to new systems that are being released, but the basic playlist controls that ST documented have not been removed.