There are similar topics but don’t work for me. Sometimes when open Cubase, it switches to Generic ASIO, sayin there is no device connected, although drivers work in all other apps on Win 10. When I try to switch back to Apollo Thunderbolt driver in Cubase’s Studio setup, option is showed but it says that there is no device installed. Still it works on all other apps except Steinberg(Cubase, Nuendo, Wavelab). Even YT. After one or two rebooting of computer everything is ok, and I can switch to Apollo Thunderbolt drivers. Anyone knows what’s happening?
I had similar problems with Apollo with Windows using Thunderbolt drivers… but sorry I can’t help you.
After spending HOURS (like ~10+) with Apollo’s (excellent) support, I still had issues…
So I ended up abandoning hopes to make it work and I switch to a plain USB port 
(and lost some features)
If you figure out a working/stable recipe, please let us know!
As for myself, as soon as I find a suitable replacement, I will sell my Apollo gear. They just don’t care enough about testing their stuff with Windows.
I would guess that you are losing the connection to the UA ASIO driver. Other apps like YT are working OK because they use Windows audio drivers.
If checking any other ASIO apps confirm this then maybe speak to UA about the driver disconnect.
Thanks for suggestion. I have to install some non-Steinberg ASIO app and check does it work when Cubase stop seeing Apollo. But in each situation, I have option to switch to Apollo Thunderbolt in Cubase Studio setup. But when I switch it says there is no hardware installed. If it loose connection to UA ASIO driver, wouldn’t it be invisible in Studio settings?
I invested too much to UA system (hardware and plugins) and I am in general very happy with it so I am not sell it probably ever 
. My issue is not so annoying, so it’s not problem from time to time (maybe once a week) restart my computer, but it would be nice if I don’t have to.