@JoGoiA, it seems the “ToonShading.usf” you downloaded is bad. (when download file from github, make sure click “Raw” button first, then save as…)
I attached the “ToonShading.usf” here, extract it into Engine/Shaders folder.
btw, enabling ‘r.ShaderDevelopmentMode’ will increase shader compile time, it’s best to leave it commented.
ToonShading.zip (702 Bytes)