A workaround that seems like it mostly fixes it for me on Windows 10…
After reinstalling the MR 1.7.7 package, you will get a popup when you start Cubase if you would like to use the Yamaha FW ASIO driver as your primary sound device. If I do not check the box to not show that window again and just click Yes, it seems to keep the Audio Device Setup on the menu. This is annoying though, as I have to click that button or press Enter during every Cubase startup.
Also, there is no need to reinstall the entire package, you can uninstall and reinstall just the MR Extensions to restore the device panel.