Hi Marco!
I noticed the same problem here with the most recent VEP 7 build.

We're on Mojave, using Digital Performer's virtual midi ports (Interapplication MIDI), VEP sees them but responds to all the 40 MIDI ports as one port - the first port enabled in the settings.
And the problem is with all the virtual ports expet VEP's own ports that works fine.

We had to install VEP 6 and load an older template (works fine in 6...)

This problem seems to be only with the server application.

VSL please fix this issue!

Update: Got a 7.0.926 installer from a friend and its working fine now. Must be the recent build.