LocalBuilder.SetLocalSymInfo() seems work fine in my below code. Can you
post a simple repro code for the problem that you ran into?
Regarding startoOffset and endOffset, they seem not affect anything. I will
follow up with this issue.

using System.Reflection;
using System.Reflection.Emit;
using System;
using System.Threading;

class TestClass
{

public static void Main()
{

        // Create an assembly.
        AssemblyName myAssemblyName = new AssemblyName();
        myAssemblyName.Name = "SampleAssembly";

        AssemblyBuilder myAssembly =
Thread.GetDomain().DefineDynamicAssembly(
           myAssemblyName, AssemblyBuilderAccess.RunAndSave);

        // Create a module 'myModule'.
        ModuleBuilder
myModule=myAssembly.DefineDynamicModule("SampleModule",
myAssemblyName.Name+".dll", true);

        // Define a public class 'myClass'.
        TypeBuilder myTypeBuilder = myModule.DefineType("myClass",
TypeAttributes.Public);

        // Define a private String field.
        FieldBuilder myField = myTypeBuilder.DefineField("myMessage",
typeof(String), FieldAttributes.Private);

        // Create the constructor.

        ConstructorBuilder myConstructor = myTypeBuilder.DefineConstructor(
           MethodAttributes.Public, CallingConventions.Standard, new
Type[]{});

        // Generate IL for the method.
        ILGenerator myConstructorIL = myConstructor.GetILGenerator();
        myConstructorIL.Emit(OpCodes.Ret);

        // Create the 'Function1' public method.
        MethodBuilder myMethod = myTypeBuilder.DefineMethod("Function1",
           MethodAttributes.Public, typeof(String), null);

        // Generate IL for 'Function1'.
        ILGenerator myMethodIL = myMethod.GetILGenerator();

        // Create local variables.
        LocalBuilder myLB1 = myMethodIL.DeclareLocal(typeof(string));
        myLB1.SetLocalSymInfo("myString1");
        Console.WriteLine("'myLB1' type is :{0}", myLB1.LocalType);
        LocalBuilder myLB2 = myMethodIL.DeclareLocal(typeof(String));
        myLB2.SetLocalSymInfo("myString2",0,0);
        Console.WriteLine("'myLB2' type is :{0}", myLB2.LocalType);
        myMethodIL.Emit(OpCodes.Ldstr, "Local value"  );
        myMethodIL.Emit(OpCodes.Stloc_0 );
        myMethodIL.Emit(OpCodes.Ldloc_0 );
        myMethodIL.Emit(OpCodes.Stloc_1);
        myMethodIL.Emit(OpCodes.Ldloc_1 );
        myMethodIL.Emit(OpCodes.Ret );

       myMethod = myModule.DefineGlobalMethod("Globalfunc",
           MethodAttributes.Public|MethodAttributes.Static,
typeof(String), null);

        // Generate IL for 'Globalfunc'.
        ILGenerator myMethodIL2 = myMethod.GetILGenerator();

        // Create local variables.
        LocalBuilder myLB3 = myMethodIL2.DeclareLocal(typeof(string));
        myLB1.SetLocalSymInfo("myString1");
        Console.WriteLine("'myLB3' type is :{0}", myLB3.LocalType);
        LocalBuilder myLB4 = myMethodIL2.DeclareLocal(typeof(String));
        myLB2.SetLocalSymInfo("myString2",0,0);
        Console.WriteLine("'myLB4' type is :{0}", myLB4.LocalType);
        myMethodIL2.Emit(OpCodes.Ldstr, "Local value"  );
        myMethodIL2.Emit(OpCodes.Stloc_0 );
        myMethodIL2.Emit(OpCodes.Ldloc_0 );
        myMethodIL2.Emit(OpCodes.Stloc_1);
        myMethodIL2.Emit(OpCodes.Ldloc_1 );
        myMethodIL2.Emit(OpCodes.Ret );

        // Create "myClass" class.
        Type myType1 = myTypeBuilder.CreateType();
    myModule.CreateGlobalFunctions();
        Console.WriteLine("'myClass' is created.");
   
    myAssembly.Save( "SampleAssembly.dll");

    MethodInfo minfo = myType1.GetMethod( "Function1" );
    Object obj = Activator.CreateInstance(myType1);
    String sret = (String)minfo.Invoke( obj, new Object[] {} );
    Console.WriteLine( "instance method return value: " + sret );

    Assembly asm = Assembly.LoadFrom( "SampleAssembly.dll");
    MethodInfo gminfo = asm.GetModules()[0].GetMethod( "Globalfunc");
    sret = (String)gminfo.Invoke( null, new Object[] {} );   
    Console.WriteLine( "global return value: " + sret );   
}
}