It seems that Cakewalk has problems scanning some Waves plugins. In my case, is with the VST3 version of Grand Rhapsody Piano. Cakewalk only shows the VST2 version of the plug-in in most cases, and the VST3 version is strangely appearing and dissapearing from the browser.
There is the scan logs: https://drive.google.com/open?id=1EH-5T343MGqMnA7Dhgu59iJdBgQlUfEB 

Hi. Have you tried to do a Vst reset and re-scan? Include all and failed plugins.
Hope it helps.
All the best.

Zargg
Hi. Have you tried to do a Vst reset and re-scan? Include all and failed plugins.
Hope it helps.
All the best.

Yeah! I have tried doing a manual scan with all of these options ticked but the problem with that particular Waves plug-in (Grand Rhapsody Piano) remains. Thank you!

Wave tech support is really helpful. I had a problem recently after an upgrade, going to Waves Center and doing a "repair" installation solved the problem. Might want to try that first, but if that fails, check with their support.

While you may be suffering from a V9 to V10 upgrade issue, it's worth it to try deleting the Waves Audio folder and the 3 subfolders (Caches, especially) from the %appdata% folder (the Roaming folder in your user account's AppData folder).
 
On my system (user name Primary): C:\Users\Primary\AppData\Roaming
 
Waves will recreate the Waves Audio folder and its contents as needed.
 
This has solved several issues for me in the past.