When porting some reflection heavy code to .net standard I encountered several breaking changes. They were all easily fixed by using GetTypeInfo(), which is where a lot of reflection functionality seems to have moved. I remember reading that it was for performance improvements.
What version of netstandard?
I just checked the project.json from that library and it appears to have been 1.6.0. It was a while back.
Also, thanks for SignalR! It's a great library!
Yes, at least when I last checked, that stuff wasn't present.