I currently have a working install of the ProRender plugin v3.5 running under Blender 3.6 LTS. Thing is, I've tried to install the material library several times and nothing happens. The only sort of error I get is if I manually try to install it using msiexec, but the error doesn't lead to anything. Same with a log generated from the install attempt. This is not a msiexec error because I can install other msi files fine.
