I actually think that standalone VIX became incompatible with Workstation version 14.1.2.

I launch VMs using the "nogui" option to the vmrun "start" command, and this stopped working ("Error: unknown error") with standalone VIX 1.17 and Workstation 14.1.2

However, the good news is that the VIX 1.17 distributed with Workstation 15 fixes the issue (and seems to be compatible) with Workstation 14.1.2 and newer (including 15 obviously).

But it is going to be very annoying if incompatible versions (of the same version number) of VIX are maintained.