Problem:

There is a problem with VXDIAG VCX NANO Toyote techstream v18 software and 2015 Toyota Avalon. The VCX will connect withthe  vehicle, diagnose and test CAN BUS communication, but
cannot read live data.
Error “Select system is not responding or not available.”

Solution:

Ensure the correct vehicle model manufactured region is selected.
Only by selecting the correct region in the software will the live data be displayed.