there should be a skill installed in the alexa app.   try disable then enable it again.   other than that, there is not much you can do about it since it sounds like the problem is at their end.   

I have an Echo Show.  The past few weeks, I will ask it to play a certain morning show.  It will pay the ads then no sound however it shows it is playing as it shows a Stop/Pause for it on the screen but again, no sound. Can hear the ads fine as well when I asked it to play music from SiriusXM it came right now.   I have unplugged it but still does it.

Some time ago, Amazon limited Alexa phone calls to 10 contacts. It used to be unlimited.

See this page from Amazon.
https://www.amazon.com/gp/help/customer/display.html?nodeId=GHKNDEFH7JCKX4DB#:~:text=As%20you%20make%20phone%20calls,%2Dto%2DPhone%20contacts%20list.

When your Alexa-to-Phone Contacts list is full
Use the Alexa app to add, remove, or update Alexa-to-Phone contacts.

Open the Alexa app.
Select More, then Settings.
Select Communication.
Select Manage Contacts.
Select Alexa-to-Phone Contacts.

OK,  I changed the name from"Both" to "Both Devices" and now it Works.
Maybe Group names have to be more than 4 characters.

SOLVED.

Matter is a "new" protocol for IoT devices that several of the major tech players are supporting (e.g. Amazon, Apple, Google). In a way, it's kind of like Zigbee (25 years old), but newer. Right now, there isn't much you can do with Matter. But a lot of devices you have probably support it, and as you update your Alexa app and Echo firmware, you'll likely see more of it. Besides just knowing it exists, there's nothing you need to know or do about it. I'm not sure if Amazon Sidewalk is based on Matter. I'm guessing it probably is.