Build fails - Type or namespace name 'SwaggerWcf' could not be found - unless I remove PublicKey attribute

Question

SwaggerWcf shows as a broken Nuget reference under project references in VS2017

If I remove the PublicKey attribute from the csproj file, the problem is fixed.

Uninstalling and reinstalling via Nuget Gui in VS creates exactly the same failure again.

Suggestions appreciated.