Oddly enough a couple of non-Waves vst3 plugs by Nembrini went missing too. Actually, most of them are not missing, but vst3 versions of SSL bundle, API Collection, CLA Vocals, and the King's Microphones have gone missing, though the vst2 versions scanned fine. So I just updated Waves Central to v.11 (not my products, but just the Waves Central software) and now some of the vst3 versions of my Waves plugins are missing. So if this happens to you then take note of the versions of what went missing (and what didn't), and a reinstallation of those legacy products is likely in order. That's right, merely updating the Waves Central software-not the products themselves-to the latest version 11 caused this. He said the solution is to reinstall the legacy 9.2 versions to restore those products whose vst3 plugs went missing.
Some of my Waves stuff are v.10 and some are v.9 and after the Waves Central update nothing happened to the v.10 stuff only my SSL Bundle, API Collection and a couple others that were v9 were affected. Just called Waves tech support and they found that, as a result of updating Waves Central to v.11 some of my legacy Waves v.9.2 vst3 products became no longer supported w/ the v.9.6 vst3 Waveshell (the vst2 plugs of those same products were scanned ok).