TTS: Speaker Group - Jitter/Stutter

I have a lot of automations that use TTS (Google_Say and Cloud_Say).

When I choose a single or multiple entities of individual speakers, it all works clearly, but not syncronised. So it’s hard to hear the voice with all the speakers talking at different intervals.

To solve this, I created a Speaker Group in Google Home app. The Group is then available as an entity in HA. I have previously setup this up 3-4 months ago and everything was working fine. Around the start of June 2023 (can’t put my finger on it), the Group started Jittering, stuttering, or the device goes into announcement mode, and nothing is announced.

I have reverted config back to individual devices and the announcement works, but they talk over each other.

I can broadcast music from my phone to the speaker group, no issues. So eliminates group issue. I can broadcast to multiple devices directly, no issue. Just as a group.

I am fairly certain this is a network issue, but asking if anyone has any idea on where to start.

Ive also tried turning on and off Multicast management on my network, IGMP etc. Seems to make zero difference.

thoughts are welcome!

Im experiencing the exact same issue. What’s interesting is that if I open an existing google_say mp3 file using the media player and selecting the path down to the file location (/config/tts in my case) the spoken text plays IN SYNCHRONY at all speakers is the selected group. If I play the same file using the Services tab, each individual speaker is a few milliseconds out of synch with the others. I’ll be glad to post all the different iterations of code I have tested without success.
The Sonos integration is one of my most useful and spouse appreciated features of HA, and has been nothing but frustrating for the past month. See this thread for additional insights: Problem with tts and sonos.
Anyone else having similar issues? Or a solution that actually works?
Sorry for the rant, just very frustrated that something that worked so well for so long, now doesn’t work well at all.

This is related to the announce support added in 2023.5. There are several threads/issues related to this. Please see Sonos media.player TTS announcement "echos" when targeting two speakers · Issue #93136 · home-assistant/core · GitHub as it has a decent summary of the changes.