Unable to Monitor Sending Speed on Mellanox NIC in Loopback Configuration

Question

I’m using a connectx4 NIC with 2 ports, connected in a loopback configuration. I have two RDMA programs running: one sends data from one port, and the other receives it on the second port. While monitoring the speeds,

I can only see the receiving speed, but not the sending speed, regardless of the tool I use (like tcpdump, nload, etc.). Can anyone explain why this is happening?