Hello,
I have the similar problem as described above. I have experienced all of the above mentioned, and additionally, each time I close Cubase it seems that something is not releasing the drivers and the card become unresponsive. When I start up dspMixFx does not show levels and when I start up yamaha control panel, the options to switch between the USB 3.1 or USB 2.0 disappear. Then, when I start up Cubase again inspector does not work, GUI has extreme lag and yamaha control panel (usb card drivers) does not start.
The workaround from above works, however, I find it kinda unacceptable to have to restart card each time i close and reopen software…
My machine has Windows 10, drivers are latest and I use Cubase AI 10.5.20 (latest update).