To reproduce:
1. Create a new project
2. Create a new script in Project window
3. In the project window right click "Open C# Project"
4. A new VS solution file (.sln) will be created with the correct project's name
5. A new VS project file (.csproj) will be created, with the name Assembly-CSharp (unavailable)

Actual result: .csproj file does not contain project name.
Expected Result: .csproj contains created project name.

Reproduced with: 2014.4.8f1; 2018.1.9f1; 2018.2.1f1; 2018.3.0a5

Note:
Opening the second time C# project in visual studio, .csproj shows correct project name.