Due to technical changes, unfortunately, Cubase 10 cannot inherit layout settings for the Project and MixConsole window made with previous Cubase versions.
Therefore, both Project and MixConsole window will open with a default configuration. For example, this affects the visibility of Zones and Tabs as well as width and height of Zones.
Projects saved with versions prior to Cubase 10 will be opened with a default window layout. The original window layout saved with the project will be discarded.
The status of Zones including selected Tabs is being stored whenever a project is being closed or saved. Next time a new empty project is being created or a project is being opened, the last applied layout settings are being used.
As a rule of thumb: The Zone setup used recently in Cubase 10 is the one that will be restored.