VIAVI TestCenter: Why only one of my streams is showing RX counters when both are showing TX correctly?
Knowledge Base - FAQ
VIAVI TestCenter: Why only one of my streams is showing RX counters when both are showing TX correctly?
You need to make sure each device has a unique MAC ADDRESS, a configuration issue (Like having 2 devices with same MAC ADDRESS) makes the DUT to get confuse and send all the traffic to the same device.
Making each device has a unique MAC address solves this issue.