Let’s assume you have ‘ACTIVATED’ these particular plugins? Moving on, open Waves Central and click on Settings (bottom Left). Under Locations you can see where your Sample libraries data folder is - BUT - you can also see where all your Waves products are stored: C:\Program Files (86)\Waves. Go there and search the various V10, V11, V12 folders and see if your plugins are actually there.
Continuing with the other options in the Settings panel, have you done a Waves ‘Complete Waves cleanup’ ? Sometimes you need to clean all your Waves plugins from the app and reinstall them. You won’t loose anything that you own. Reinstall them and activate them. Then ‘Clear Central cache’.
Then open Cubase again and see if Cubase found your plugins. I’ve had Waves on my computer via a phone link and this is what they do to sort things if things aren’t working as they should. In 15 years it’s happened 3 times. I’ll check back.
Another thing, when you install the plugins, skip all the versions you won’t use, ‘axx’, VST2, etc. Just load the VST3 plugins. This will keep your plugins in Cubase organized and not full of fluff that it can’t use.