Visual Studio 2015 - Webforms - Concrete Classes Not Recompiling?

My Visual Studio 2015 C # project has web forms and classes defined in a folder App_Code

. When building / restoring my solution, some of the specific classes in this folder are never recompiled - after compilation, their code does not change (although it would seem they did commit compilation).

This shows up as runtime error messages for the code I just changed, was unable to place breakpoints, etc.

I tried:

• Rebuild

• Removing ASP.NET Temporary Folders

• (No "clean solution" because these are web forms)
• Runs as admin

The only solution that works : reopening Visual Studio.

Illustration:

EDIT:

Now I found that deleting the folder C:\Users\kobydo\AppData\Local\Temp\Temporary ASP.NET Files

and then running the build also fixes this issue. But this is not a real solution.

Any idea why this is happening?