Well, I’ve been struggling for hours…
(sorry, my Cubase is in french: I am not sure about the name of function in english)
It’s a relatively small project and I wanted to remove the group (or bus?) folder.
But since this fool operation, if I want to create a group, it is displayed in the mixer, in “Visibility” window, but does not appear in the project window. It’s not a big deal, you might say, since I can access it from the mixer window. But it drives me crazy!
On the picture you can see the fx reverb that I took out of the folder. The next two groups (drums and test) do not appear. “Pistes Groupe” is invisible.
Hmm, I’m not certain, but have you tried clicking on Write enable on mixer, There is a bug for input channels where they will not show up on arrange page until you click this. Perhaps it will work for the missing group channels too? I assume you have not hidden grroups using the ‘track visability configurations’ options? 
Edit : I mean write enable on the mixer for the group channels that are not showing, just to be clear.
Tracks can be filtered here as well as the ‘visibility’ panel in the inspector, just incase you were not aware.
Thank you. I just closed my session and will try tomorrow. But I already can say it is not masked in the “filter track type”. I don’t know the preceding idea about "write enable"in mixer. Let’s see…
Good luck, I only suggest trying that in case it is related to this bug View Input/ Output tracks in main window? Just seems it may be worth a try
