I have an ASP.NET MVC project, with an ASP.NET web api defined as an area in this project. So the structure is the following:
MVC Web
Controllers
View
Open:
Tools - Options - Debugging - General
Select:
Enable .NET Framework source stepping
Enable source server support (all options selected)
Open:
Tools - Options - Symbol
Select Microsoft Symbol Servers
Click Load All Symbols
Rebuild the project.
Select:
Clean
Rebuild
Rebuild solution and try again.