Cubase 13 Pro, Windows 10.0.19045 Build 19045, Core i7-5840K with 32 GB RAM running on PCI-E SSD.
When I have a second window open just showing my channel mixers, I cannot see more than the 27 (maximum allowed) channels at a time, even when moving the slider left and right, I have to hide tracks in order to see the ones further to the right?
Please see attached video for behaviour.
Thanks.
There are three Mix Console Zones. Only the center one is scrollable, the left and right most zones are pinned and always visible. In your video you have pinned/locked more channels to the left zone than can be displayed with your monitor resolution.
Change your channels from the left to the center zone to be able to scroll through them.
I see, thanks for the prompt reply 
This is a little frustrating, as I use the left zone for my tracks, the middle zone for my group channels and the right zone for Mastering and outputs, will have to find another way to work…
Fact of the matter is, there is never enough space on the screen for mixer channels. Fortunately, Cubase offers some handy features to show/hide channels.
First off there are 4 Mix Consoles in Cubase Pro that can be independently configured in what channels they show. Next, I recommend making use of Channel Visibility configurations and add key commands to those.
Once you get used to these features, you’ll be flying through even very large channel counts.
I think it is better to think about it in terms of which & how many Channels you want to to be able to scroll and which you want to always be pinned to one side or the other. Then budget your space accordingly.
In normal use I don’t pin Channels to the left side at all, only on the right and everything else scrolls.
That is indeed a better way to think of my workflow, thank you.