Roslyn INamedTypeSymbol.GetMembers() throws Method Not Found Exception on Roslyn API

I am trying to use Roslyn to navigate to method declaration. I have Namespace name, class name and method name. Below in the code sample I am able to get classReference variable populated. But as soon as classReference.GetMembers() is called I am getting Method Not Found Exception. Although when I execute classReference.GetMembers() in intermediate window (Visual Studio debug mode) it gives me correct method names.

public async void NavigateToMethod(string className, string methodName)
    {
        Microsoft.CodeAnalysis.Solution sol = Workspace.CurrentSolution;
        foreach (Microsoft.CodeAnalysis.Project project in sol.Projects)
        {
            bool found = false;

            Compilation compilation = await project.GetCompilationAsync();
            INamedTypeSymbol classReference = compilation.GetTypeByMetadataName(className);
            List<ISymbol> l = classReference.GetMembers().ToList<ISymbol>();
            Debug.WriteLine(l);



            foreach (ISymbol isymbol in classReference.GetMembers(methodName))
            {
                IMethodSymbol methodSymbol = isymbol as IMethodSymbol;
                CancellationTokenSource cts = new CancellationTokenSource();
                if (Workspace.TryGoToDefinition(methodSymbol, project, cts.Token))
                {
                    found = true;
                    break;
                }
            }
            if (found)
            {
                break;
            }
        }
    }

Exception System.MissingMethodException

HResult=0x80131513

Message=Method not found: 'System.Collections.Immutable.ImmutableArray`1 Microsoft.CodeAnalysis.INamespaceOrTypeSymbol.GetMembers()'.

This is confusing. When I looked at the Microsoft.CodeAnalysis.INamespaceOrTypeSymbol documentation the GetMembers() method exists (public) and I am referencing the assembly which has this method, also it is available at runtime.

Just note classReference.GetMembers(methodName) only works in Intermediate window, not sure what is going on.

package.config

<packages>
  <package id="Microsoft.CodeAnalysis" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.Analyzers" version="2.6.0" targetFramework="net461" developmentDependency="true" />
  <package id="Microsoft.CodeAnalysis.Common" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.CSharp" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.CSharp.Workspaces" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.VisualBasic" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.VisualBasic.Workspaces" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.CodeAnalysis.Workspaces.Common" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.Composition" version="1.0.31" targetFramework="net461" />
  <package id="Microsoft.Net.Compilers" version="2.7.0" targetFramework="net461" developmentDependency="true" />
  <package id="Microsoft.VisualStudio.CoreUtility" version="15.6.27740" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.ImageCatalog" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Imaging" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.LanguageServices" version="2.7.0" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.OLE.Interop" version="7.10.6071" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.SDK.EmbedInteropTypes" version="15.0.16" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.15.0" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Framework" version="15.6.27413" targetFramework="net461" />
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  <package id="Microsoft.VisualStudio.Shell.Interop.10.0" version="10.0.30320" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.11.0" version="11.0.61031" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.12.0" version="12.0.30111" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.15.3.DesignTime" version="15.0.26929" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.15.6.DesignTime" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.8.0" version="8.0.50728" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Shell.Interop.9.0" version="9.0.30730" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Text.Data" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.TextManager.Interop" version="7.10.6071" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.TextManager.Interop.8.0" version="8.0.50728" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Threading" version="15.6.46" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Threading.Analyzers" version="15.6.46" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Utilities" version="15.6.27413" targetFramework="net461" />
  <package id="Microsoft.VisualStudio.Validation" version="15.3.32" targetFramework="net461" />
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  <package id="System.Collections" version="4.3.0" targetFramework="net46" />
  <package id="System.Collections.Concurrent" version="4.3.0" targetFramework="net46" />
  <package id="System.Collections.Immutable" version="1.5.0-preview1-26216-02" targetFramework="net461" />
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  <package id="System.Linq" version="4.3.0" targetFramework="net46" />
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  <package id="System.Xml.XPath.XDocument" version="4.3.0" targetFramework="net46" />
</packages>

The problem was System.Collections.Immutable version, I was using 1.5.0-preview that happened because I clicked on update all in nuget package manager UI.

<package id="System.Collections.Immutable" version="1.5.0-preview1-26216-02" targetFramework="net461" />

As soon I downgraded System.Collections.Immutable to version 1.3.1 the exception was gone.