From time-to-time, I have this weird situation with ReSharper and Visual Studios (different versions of both) where my code is compiling, but ReSharper is highlighting some things in red. I think there might be a few different solutions to this problem, and I'll add others here if I come across them. The solution that worked for me this time is just to delete the .suo files.

Another solution that has worked in the past is to clear the ReSharper cache and restart Visual Studio.

ReSharper > Options > Environment > General > Options > General 

Click the Clear Caches button.