[tuyuri]

It's important to say that BURP only deals with http like requests ( http/https websockets ) and the app can be sending/receiving data via other protocols, the same way you can't see whatsapp messages via burp [0]

[0] - https://security.stackexchange.com/questions/153944/burp-wit...

[DarthGhandi]

This is an excellent point.

Checking wireshark should really be done first.