Hey All,
Just as an FYI, I got the new Waves L4 Ultramaximizer working on Vegas Pro 21 Edit.
I went to C/Program Files/Common Files/VST3, I then made a folder and named it Waves and then I moved the WaveShell-VST3 16.3_x64.vst3 file to THAT folder, then in Vegas Pro, I went to Options/Preferences/VST Effects and clicked Add Path and pointed it to the new folder I created in Common Files/VST3/Waves