Hello VC,
It is my understanding that you are unable to create a new live script or open a '.mlx' file in Live Script.
Please try the workaround mentioned in the below MATLAB Answers link to see if the issue is resolved-https://www.mathworks.com/matlabcentral/answers/1815470-matlab-live-editor-unable-to-open-this-file-in-the-current-system-configuration