To reproduce:
1. Open project attached by the user
2. Switch platform to iOS
3. Edit-> Project Settings -> Player and select .NET 4.6 framework
4. In project window go to Assets -> Plugins -> iOS and select "SomePlugin" file
5. Observe console window and Inspector window

Expected: In the inspector, all Framework Dependencies should be available, errors shouldn't appear.
Actual: There is only one option in Framework Dependencies, errors and warnings appear in the console.

Note: This happens only when platform in the Plugin Inspector is set to iOS and framework version is 4.6

Reproduced with: 2017.1.0b1, 2017.1.0f3, 2017.2.0b3
Earlier versions don't support .NET 4.6

Fixed in 2017.3.0b1
Backported to 2017.2.0p1