Instrumenting .Net Core 2.1 with VsInstr x64 /coverage showing Error VSP1026

Hi,

I am using VS2017 Enterprise edition Version 15.9.4. While trying to instrument a dll of the console application to generate coverage report using VsInstr gives Error VSP1026. I am in need of generate code coverage using Vsinstr and VSPerfCMd for .Net Core application. Project Debugging information set to 'Full' in Advance build settings (Not 'Portable'). 

E:\Github\CoreCodeCoverageExample\CalcDLL\bin\Debug\netcoreapp2.1>vsinstr /coverage CalcDLL.dll
Microsoft (R) VSInstr Post-Link Instrumentation 15.0.28218 x64
Copyright (C) Microsoft Corp. All rights reserved.

File to Process:
   E:\Github\CoreCodeCoverageExample\CalcDLL\bin\Debug\netcoreapp2.1\CalcDLL.dll --> E:\Github\CoreCodeCoverageExample\CalcDLL\bin\Debug\netcoreapp2.1\CalcDLL.dll
Original file backed up to E:\Github\CoreCodeCoverageExample\CalcDLL\bin\Debug\netcoreapp2.1\CalcDLL.dll.orig

Error VSP1026: Coverage is not supported on libraries that do not reference MSCorLib. This is often the case for Portable Libraries.

Note: I'm able to instrument dlls of .Net Framework 4.6 but NOT .Net Core 2.1

Any Suggestion to resolve this issue would be highly appreciated

Thanks,

Mohan