I have a stereo pair of Ones with a Sub Gen 3, and another stereo pair of Ones on the other side of the same room (Room is approx 8m square). These are grouped together to play as a single room, which on the whole is good enough. Voice control via Sonos is disabled (all microphones are set to off) as it was terrible, but we have an Amazon Echo Dot which is set to play music on the Sonos group as its default speakers.
Problem is that when manually starting a new track for this group from the Sonos app (or any other music app that supports casting, E.g Amazon Music, Plex) the track starts ok then about 1-2 seconds after starting the volume dips by about 50% for 5-10s before returning to selected level. This also happens when a new track starts via Alexa voice command from the Echo Dot. Also happens in other rooms where we also have pairs of Ones, given that these are the common element I'm inclined to think they're to blame. The displayed volume level doesn't appear to change in app whilst the output dips by 50%.
Anyone else having this and / or has any tips to resolve would be much appreciated!