Recording in WAV format fails when sending a DTMF tone

Hi @xquanluu, I'm testing recording with WAV format and it seems to be working all fine *unless a DTMF code is sent*. I've created a sample app at "https://public-apps.dev.bookline.io/hello" to reproduce the issue.

If you place a call with this app without pressing any DMTF code it's OK. If you place a call with this app and you press any digit at any time the recording is not created but I'm unable to see any error logs on the feature-server. Any hints on what we could troubleshoot here?

Start with the linked sample app and reproduce the call twice: once without DTMF and once after pressing a digit. Trace the feature-server recording path and its error output; done means WAV recording is created in both cases and the failure, if any, is covered by a reproducible test.

Written by the indexing model from the issue text.