I still have issues with some Waves plugins, even after update to WL 11.20.
Some of them (always more or les the same ones) are missing regardless of what I do; full detection, re-installation, Waves cleanup etc.
After some more testing I have narrowed it down to maybe be related to the Setting Location in Global Preferences.
I usually use a “Specific Folder” on an external SSD I can take with me, but if I change that to “Common for All Users”, force a full detection and restart WL it scans all Waves plugins correctly the first time.
I don’t know why, but it may have something to do with this setting, so maybe you can see if you can recreate it on your side!?