This issue has also affected me and others on here. I think you mean the top item on the menu- ‘Audio Hardware Setup’ - is missing, so you can’t switch audio drivers within Cubase. This was happening to me as well. The workaround I have found which has ‘fixed’ it for me is to re-install the ‘Tools for UR824’ software. Then, when you start Cubase and it is loading, you get a message box asking you which driver you want to use. This little message has a tickbox at the bottom saying ‘Do not ask me this again’. DO NOT tick this box, just select the driver you want and let Cubase carry on loading. I found this fixed it for me and the missing menu item has always been there since I did this. It means you have to choose the driver each time you start Cubase, but this is no hassle compared to having missing menu items!!!
I am on Windows 7 but apart from that our systems are very similar.
Your post is 2 months old now so you may have sorted it by now, but if not try this. It’s working over here…