Hi,
I faced some problem after upgraded to 2019 with latest version of LWRP, then I faced this particular error when trying to override ShaderPropertiesGUI function
error CS0506: 'TCP2_MaterialInspector_LWRP_SG.ShaderPropertiesGUI(Material)': cannot override inherited member 'BaseShaderGUI.ShaderPropertiesGUI(Material)' because it is not marked virtual, abstract, or override
Base on the documentation(Class BaseShaderGUI | Package Manager UI website), the ShaderPropertiesGUI is a virtual function which is overrideable, but seem like there some problem with latest LWRP version
Thanks.