Asterisk stops sending RTP after a RTCP paquet

Hi everyone, I’m really puzzeled by this one, perhaps someone can shed some light on this. Here goes:

I have an asterisk (11.5.0) that is working fine, processing (5000 calls per day). This asterisk is connected to several SIP providers. One of my customers reported to us one way audio during a call. I got a paquet capture and I see the call being setup normally, then RTP is exchanged both ways between me and my sip provider, then after 30 seconds, I see asterisk sending a RTCP paquet to my sip provider. Following this RTCP paquet, asterisk stops sending RTP for some reason. My provider continues to send RTP to me however…

I thought of disabling rtcp but looks like its mandatory part of RTP.

Basically I’m pretty stuck on this one. It’s not something that happens frequently but I would like to figure out what could cause this. If anyone has an idea on when I should look it would be much appreiciated.