An AOD application that uses Text to speech has been deployed to the Avaya experience portal. The application does not play the TTS and we hear silence instead. No error is being logged in the log files and the application is being executed as if the TTS has been successfully played back.
1) What could be the issue?
2) How can we investigate the matter as no error is being logged?

You need to take a look into the AVB log on MPP. Did you assign TTS speech server to the app when you configure it on EPMS?