Shuffle with loop mode Alexa failure

I am unable to get my Sonos One to both shuffle and loop an Amazon Music playlist using Alexa. The following steps are taken:
1. "Alexa... Shuffle Arnold music" (Arnold is my dog)
2. Sonos One starts shuffled version of the playlist, stating it is playing on the Sonos.
3. "Alexa... Loop Mode"
4. Sonos One acknowledges Loop Mode is turned on.

After that, the playlist does not loop.

Is this a bug?