Solved issue with below answer from mSpot Inc
First make sure the Toolkit is completely removed from your solution and
Using NuGet, uninstall the Toolkit
Check the project Reference folder. If it still has a reference to the
Toolkit, delete it.
In Windows, look for the packages folder in your solution folder. If you
aren't using any other NuGet packages, delete the packages folder.
Delete any Toolkit dll files in the solution and project subfolders.
Then reinstall the Toolkit with NuGet.