I want to buy a Waves plugin to use in Mulch (Windows), so I downloaded the latest Waves installer/manager software and installed the demo of the particular plugin I want to use. Waves plugins don't work with simple .dll files, it installs everything into its own folder and then puts a single .dll file into your VSTPlugins folder. All good so far, only in Mulch when I click on that WaveShell.dll to add a plugin, nothing happens. :( It is the 32 bit version, so should work.
I've hads other plugins not load in Mulch recently too, wheras it always used to be one of the best/most stable hosts that would run almost everything.