Vst Plugin Waveshell1-vst3 11.0-x64 -vst3- -

You open an old project. The DAW says it cannot find the Waves plugin, but you see the Waveshell file in the folder. Cause: Your Waves Version is mismatched. You saved the project using Waves V12, but currently have V11 installed (or vice versa). Waveshells are not backward-compatible. Fix: You must install the specific WaveVersion used to save the session, or bounce the audio/track to audio (freeze/flatten).

Having Waveshell1 present means you have at least the core mixing and mastering effects installed. Vst Plugin Waveshell1-vst3 11.0-x64 -vst3-

C:\Program Files (x86)\Waves\Plug-Ins V11 You open an old project