On UObject you should take each instance from the array and then manually generate the Guid value in a for each loop as soon as you instantiate them;
This is what was in that example.
The thing you have to plan is, SGUID values should be unique for each instance, not invalid and, always the same set across multiple application runs.
For important objects, some people create a data table of Guid values on Excel and always assign these guids to the same array of Object instances on their SGUID property, like MMOs do.
Unreal also implements a “Actor Guid” but that is only reliable for permanently spawned actors.