This is a .net standard 2.0/net 4.6/4.7.1 issue which was improved in 4.7.2:
"In .NET Framework 4.7.2 we have addresses the known runtime issues
with .NET Standard 2.0. We made changes to the runtime to ensure
that you don’t need additional files deployed along with your .NET Standard library"
So, run Visual Studio 2017 Installer and install .Net Framework 4.7.2 and the Target Pack and target your app as .net 4.7.2.
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…