Status Update
Some players still appear to be receiving occasional silent responses. We’ve therefore moved all sound files to the same endpoint as the skill itself – which allows us to rule out audio URLs as the cause.
Requests are processed correctly on our side, but some devices still remain silent from time to time. No errors are reported by Alexa or by the devices themselves.
We’re still waiting for a response from Amazon and will continue narrowing down the issue on our side in the meantime.