Does the Roberts radio support Chromecast as well? If not, that might explain it as the Spotify app seems to fail if the target device supports both Connect and ChromecastI've found that you can either go through the Spotify app and google cast it, or go to open.spotify.com in your browser (I use Chrome) and actually connect using Spotify Connect as before. This is consistent between ios and Windows 11, app does not Spotify Connect, Chrome browser does
I have no problem doing Spotify connect to my Roberts radio so this seems to be an inconsistency between Spotify app and Wiim products only. Hopefully Spotify put up a fix soon