Changing volume playing over Spotify connect UNMUTES all SONOS speakers in group

[drlove76]

Plan Premium

Country Sweden

Devices

(iPhone XS Max, iPhone 6, iPad, Macbook Air 2018)

Operating Systems

(iOS/iPadOS 13.1.2, Mojave)

My Question or Issue

1. Playing using Spotify Connect to our Sonos speakers that is grouped and some of them is muted.

2. Changing music volume on our device (iOS/iPadOS/macOS) the master volume on that Sonos-group is changing (as expected) and ALL speakers get UNMUTED.

Problem: The muted speakers is not supposed to play anything!!! Unless we unmute them by choice or by pressence (via home automation system). Why is this happening? My whife is getting crazy, she is not using the Sonos app and can't re-mute the speakers that should be muted.