This might be a rookie mistake but, everything was working nice and fine with the cameras in my scene and then, when saving a seemingly unrelated script my cinemachine brain just kinda gave up and stopped detecting any virtual cameras.
No compile errors, no warnings, no debug messages.
I checked in all my other scenes and everything was fine.
Then I duplicated the problematic scene, deleted the cinemachine brain and virtual cameras, added new ones, and they worked without any trouble.
Does anyone know what happened there?
I would like to know if I can fix this, because many of my animations/timelines depend on cinemachine 
I’m using unity 2019.1.8f
Some screenshots:
The CMBrain will only detect vcams that are on the layers not filtered out by the camera’s layer mask. This is to support multi-camera setups (e.g. splitscreen). Is it possible that somehow the layers or layer mask got messed up?
Also FYI you can just copy/paste images directly in the forum post. Much easier 
Thank you, that was the issue, layers were in the incorrect order!