Does the xsd.exe tool provided with Visual Studio generate the SchemaLocation attribute (in the xs:import) when generating XSDs from plain old C# objects?
I am finding that my XSDs that were generated are not valid because the xs:import will import a namespace and not provide the relative schemalocation value prompting the below
Imported Schema for namespace 'urn:company-event-namespace' was not resolved.
As you've found, it does not generate that attribute. This may have to do with the fact that it would not use that attribute if the attribute were present in a schema it was reading.
As shown in this anwser you can add manually add an attribute. Because the xsd tool generates a partial class, you can add this attribute in a seperate file, so you don't have to modify a generated file.