Call Monitoring - Audio from 3CX - no data

[GoodmanGroup]

We have a site that is experiencing some infrequent, intermittent call quality issues. When I turned on call monitoring for the extension, there is no data on the Audio from 3CX side. Any idea why?

Also, should it be in transcoding mode? For a call that's PCMU on both ends I expected to see proxy mode.

 

[ivank]

Missing RTCP report from the trunk, PBX cannot evaluate its own outgoing stream without it. Overall the stats are great.
Transcoding mode depends not only on codecs but other stuff as well: call recording, PBX delivers audio, etc.