[Connect GrandMA to Vision 2021]

Which version of Vision are you using?
Mac or Windows?
And probably most importantly, do you have the VizKey from MA?

We have identified an issue with Vision 2023 on Windows that prevents the connection.
The issue will be fixed in a soon to be released service pack.

[Connecting Vision 2.3 PC using Enttec USB PRO Box]

Enttec dmx pro drivers were dropped many years ago.

The primary interface for Vision are networks protocols like Art-Net or sACN rather than USB interfaces.