I was troubleshooting an issue with media connectivity in Lync Web App and needed to gather additional information on what was happening with the Lync Web App. By default LWA logs some basic information. Unfortunately this didn't tell me what I needed. In order to get more detailed logs from LWA, you just need to append the following to the meeting join URL:
https://meet.test.deitterick.com/william.cooper/YL6HFCPK?sl=1&log=full
Adding &log=full to the end of the meeting join URL will cause the Lync Web App to log additional information. The logs that LWA creates are stored here:
C:\Users\<username>\AppData\Local\Microsoft\LWAPlugin\Tracing
Specifically, the file you are looking for is:
LWAJSPersistentx.log
Where x is a number, usually 0 or 1. Opening up the file, you will see a whole bunch of information including information about WebTicket, MRAS, and ICE candidates among other information.