After upgrade 3.10 to 3.20 , nopcommerce is not building dll files properly. i cant see the changes i made in my plugins. what i figure out is that in web project there are dll files of plugins we create, it does not re-build these files. i dont know why. I have applied the latest patch to VS 2012.
This sounds like problem with Visual Studio. There was however change to how NopCommerce is built, instead of batch files you build and publish from within Visual Studio.
Also solution was upgraded to Visual Studio 2013 format, maybe there is backward compatibility issue.