CommandLine v1.9.71.2 is incompatible with .NET Framework 4 Client Profile

Question

I am currently transitioning between Visual Studio 2010 (with .NET v4.0) and Visual Studio 2015 (with .NET v4.6.2). I'm maintaining a production version of my application on 4.0 and a development version on 4.6.2. As an aside: Once the development version is complete and released to production, I'll be working exclusively in 2015 with .NET v4.6.2.

At the moment, I'm adding a console application project in my production version (.NET 4.0) and I'm trying to add a reference to the C# Command Line Parser library. I'm getting the following error.

The project I have created is indeed targeting .NET Framework 4 Client Profile. What's interesting, however, is that I have another project in this solution, also targeting .NET Framework 4 Client Profile, that already has a reference to CommandLine v1.9.71.2 (the same version that is incompatible here) and it builds without issue.

My intuition is that something happened when I installed .NET 4.6.2, but I'm confused. Any ideas on how to resolve this (and why this is happening)?