After nearly 2 years of being fine, many of my 3rd party VSTi’s had disapeared from my VSTi instruments list recently. Directing many of them seemed to make them show up in my list, but when I closed & reopened Cubase they weren’t getting saved no matter what I tried. I finally just do what I’ve done before…that is just find the .dll & manually placed them in a folder that ‘would’ work AND 'remember…this bs problem solved!