Apple Music works from Sonos app but not from Alexa

Until recently I regularly used my Amazon Echo Dot (Alexa device) to start playing music from Apple Music on my Sonos speakers using the Alexa Sonos skill. Recently it stopped working--either nothing plays or Alexa gives some “I can’t do that” error. If I have the Sonos app open on my phone while this failure is happening, I can tell my request to Alexa has succeeded in part because I see a stream of messages like this in the app:

In the Sonos app I can search for something and pick a match from Apple Music and successfully play the matching track. All of this implies to me that there’s neither a networking problem nor a problem with my Sonos system’s connection to Apple Music. (I did the “reauthorize” operation just in case; it didn’t help.)

Any ideas?