Amazonechocontrol: announcement for Sonos One

using Sonos One (with latest 10.6.1 firmware) also with Alexa functionality and stuff.
Is the Sonos One not capable of using echo stuff like “announcement”?

my things:

Bridge amazonechocontrol:account:binders "Amazon Account" @ "daheim" 
	Thing echo	echo_Kueche	"Alexa" @ "Küche" [serialNumber="G09xxxxxxxxxxxxx"]
	Thing echo	echo_Schlafen	"Alexa" @ "Schlafen" [serialNumber="e6xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx"]

My items:

// Commands
String Echo_Kueche_Announcement    "Announcement"    (Alexa_Kueche) {channel="amazonechocontrol:echo:binders:echo_Kueche:announcement"}
String Echo_Kueche_TTS             "Text to Speech"  (Alexa_Kueche) {channel="amazonechocontrol:echo:binders:echo_Kueche:textToSpeech"}

String Echo_Schlafen_Announcement   "Announcement"   (Alexa_Schlafen) {channel="amazonechocontrol:echo:binders:echo_Schlafen:announcement"}
String Echo_Schlafen_TTS            "Text to Speech" (Alexa_Schlafen) {channel="amazonechocontrol:echo:binders:echo_Schlafen:textToSpeech"}

In my rule, I let the announcement go through with 100% and then the volume is set back to previous level automagically.

import org.eclipse.smarthome.model.script.ScriptServiceUtil

var Timer tFamCal_1
var Timer tFamCal_2
var Timer tFamCal_3
var Timer tFamCal_4
var Timer tFamCal_5
var Timer tFamCal_6

val echoAnnouncement = [ String room, String announcement |
	var echos = newArrayList("Kueche", "0")
	// which room is the announcement?
	if (room != "all" && room != "") {
		echos.set(0, room)
	} else {
		echos.set(0, "Kueche")
		echos.set(1, "Schlafen")
	// make the announcement
	echos.forEach[ echo |
		if (echo != "0") {
			var CurrentAnnouncment = ScriptServiceUtil.getItemRegistry?.getItem("Echo_"+echo+"_Announcement")
			var jsoncmd = '{ "sound": true, "speak": "'+announcement+'", "title": "Announcement", "volume": 100}'
	logInfo("echoAnnouncement", "echos: [{}]",echos)		

rule "Announcement testen"
	Item Echo_TestItem received update
	echoAnnouncement.apply("all", "das ist ein Test")

now if I trigger the Echo_TestItem, the Announcements go through, the echo (Gen3) in the “Kueche” triggers the announcement as expected, the one in “Schlafen” does nothing… but not quite, if music plays on “Schlafen” it will get louder (too short for the “das ist ein Test” sentence…) and gets back to previous level - sort of intended.

So, is the Sonos One not able to “announce” something? because the Echo_Schlafen_TTS item works. But why does it change the volume then?

Be careful with future firmware updates: