Unable to have 2 VST rack instruments running

Strangest thing. I dont have the issue in 7.5 but when I create 2 rack instruments in Cubase 8 the sound stops working on both after the second is created.

I did a fresh install of cubase 8 with no additional plugins added to double check it wasnt a bad install of a vst.

Steps for repro:

Start Cubase
Create an empty project
add a rack instrument (i added prologue)
create the midi track along with it.
sound works and comes from channel output.

create another prologue rack instrument
create the midi track along with it
neither midi tracks or instruments playback anymore.

If i close the project and create a new one. The first rack instrument I create doesnt work.

After that, I try and close cubase and it wont close, so I have to close via the task manager.

After a reload of cubase, the first rack instrument works again, but the second causes the issue again.

works fine here.

Are you on 7.5 or 8? Works fine for me in 7.5 but not 8.

Yes on both accounts. It works in 7.5 and 8

Any ideas what it could be? Here’s a quick video I made to show the issue.


After more experimentation I noticed something possibly even stranger…

Create a new empty template
Create a vst instrument rack (prologue)
Instrument works great
In the inspector I click on edit instrument channel settings
After I click that, the instrument no longer plays through the channel (even if i didnt change anything)


If i create a new empty template
create an audio track and drop in an mp3
enable the click track
and hit play
everything works

if i add a vst rack instrument (prologue) everything still works and is still playing
if i add a second vst rack instrument everything stops playing including the click track.