When maximizing the IQ rate results non-synchronized TX-RX

[VDN1]

I'm experimenting with the LabVIEW Comms 2.0 project entitled "USRP RIO 120-160 MHz BW Single-Device Streaming".. My problem is when I try to use the maximum IQ rate 120Mhz, the RX signal seems non synchronized with the TX waveform. It only synchronizes when I use below 50Mhz IQ rate. Can someone explain to me why? Also, is this possible to overcome?

I'm using USRP 2940R.

[Chase.E]

What synchronization are you referring to? Could you show us pictures of the 120M and 50M rates for comparison as well as all other front panel connections and wiring?