RFNOC : GRAPH ERROR x310 + TVRX2
USRP X310 with 01 TVRX2 daughterboard Latest uhd (v4.2.0.0) X310 + SBX = working without any issue
uhd(v3.14) = TVRX2 gets detected without any issue

Is only uhd_usrp_probe failing, or also other utilities/examples?
Did you build UHD from source? If so, can you please rebuild with -DUHD_LOG_MIN_LEVEL=trace.
In any case, can you please set the log level to max (export UHD_LOG_LEVEL=trace, export UHD_LOG_CONSOLE_LEVEL=trace) and post the output here?
I think you should reinstall you ubantu OS and reinstall UHD+gnuradio+gr-ettus with a standard version and step.
Closing due to lack of feedback.