I have R# installed, sometimes it works, sometimes it doesn't. I usually just close the file and reopen it and it'll find the methods.
I tried disabling R# and just VS intellisense and it does the same thing. Looking at the implementation that I'm trying to look for, it was able to find it in the correct namespace. Is there a chance that there are two assemblies that are in conflict that's why it cannot find the method?
